spi: tegra114: flush fifos

[mirror_ubuntu-bionic-kernel.git] / drivers / spi / spi-tegra114.c

/*
 * SPI driver for NVIDIA's Tegra114 SPI Controller.
 *
 * Copyright (c) 2013, NVIDIA CORPORATION.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/reset.h>
#include <linux/spi/spi.h>

#define SPI_COMMAND1                            0x000
#define SPI_BIT_LENGTH(x)                       (((x) & 0x1f) << 0)
#define SPI_PACKED                              (1 << 5)
#define SPI_TX_EN                               (1 << 11)
#define SPI_RX_EN                               (1 << 12)
#define SPI_BOTH_EN_BYTE                        (1 << 13)
#define SPI_BOTH_EN_BIT                         (1 << 14)
#define SPI_LSBYTE_FE                           (1 << 15)
#define SPI_LSBIT_FE                            (1 << 16)
#define SPI_BIDIROE                             (1 << 17)
#define SPI_IDLE_SDA_DRIVE_LOW                  (0 << 18)
#define SPI_IDLE_SDA_DRIVE_HIGH                 (1 << 18)
#define SPI_IDLE_SDA_PULL_LOW                   (2 << 18)
#define SPI_IDLE_SDA_PULL_HIGH                  (3 << 18)
#define SPI_IDLE_SDA_MASK                       (3 << 18)
#define SPI_CS_SW_VAL                           (1 << 20)
#define SPI_CS_SW_HW                            (1 << 21)
/* SPI_CS_POL_INACTIVE bits are default high */
                                                /* n from 0 to 3 */
#define SPI_CS_POL_INACTIVE(n)                  (1 << (22 + (n)))
#define SPI_CS_POL_INACTIVE_MASK                (0xF << 22)

#define SPI_CS_SEL_0                            (0 << 26)
#define SPI_CS_SEL_1                            (1 << 26)
#define SPI_CS_SEL_2                            (2 << 26)
#define SPI_CS_SEL_3                            (3 << 26)
#define SPI_CS_SEL_MASK                         (3 << 26)
#define SPI_CS_SEL(x)                           (((x) & 0x3) << 26)
#define SPI_CONTROL_MODE_0                      (0 << 28)
#define SPI_CONTROL_MODE_1                      (1 << 28)
#define SPI_CONTROL_MODE_2                      (2 << 28)
#define SPI_CONTROL_MODE_3                      (3 << 28)
#define SPI_CONTROL_MODE_MASK                   (3 << 28)
#define SPI_MODE_SEL(x)                         (((x) & 0x3) << 28)
#define SPI_M_S                                 (1 << 30)
#define SPI_PIO                                 (1 << 31)

#define SPI_COMMAND2                            0x004
#define SPI_TX_TAP_DELAY(x)                     (((x) & 0x3F) << 6)
#define SPI_RX_TAP_DELAY(x)                     (((x) & 0x3F) << 0)

#define SPI_CS_TIMING1                          0x008
#define SPI_SETUP_HOLD(setup, hold)             (((setup) << 4) | (hold))
#define SPI_CS_SETUP_HOLD(reg, cs, val)                 \
                ((((val) & 0xFFu) << ((cs) * 8)) |      \
                ((reg) & ~(0xFFu << ((cs) * 8))))

#define SPI_CS_TIMING2                          0x00C
#define CYCLES_BETWEEN_PACKETS_0(x)             (((x) & 0x1F) << 0)
#define CS_ACTIVE_BETWEEN_PACKETS_0             (1 << 5)
#define CYCLES_BETWEEN_PACKETS_1(x)             (((x) & 0x1F) << 8)
#define CS_ACTIVE_BETWEEN_PACKETS_1             (1 << 13)
#define CYCLES_BETWEEN_PACKETS_2(x)             (((x) & 0x1F) << 16)
#define CS_ACTIVE_BETWEEN_PACKETS_2             (1 << 21)
#define CYCLES_BETWEEN_PACKETS_3(x)             (((x) & 0x1F) << 24)
#define CS_ACTIVE_BETWEEN_PACKETS_3             (1 << 29)
#define SPI_SET_CS_ACTIVE_BETWEEN_PACKETS(reg, cs, val)         \
                (reg = (((val) & 0x1) << ((cs) * 8 + 5)) |      \
                        ((reg) & ~(1 << ((cs) * 8 + 5))))
#define SPI_SET_CYCLES_BETWEEN_PACKETS(reg, cs, val)            \
                (reg = (((val) & 0xF) << ((cs) * 8)) |          \
                        ((reg) & ~(0xF << ((cs) * 8))))

#define SPI_TRANS_STATUS                        0x010
#define SPI_BLK_CNT(val)                        (((val) >> 0) & 0xFFFF)
#define SPI_SLV_IDLE_COUNT(val)                 (((val) >> 16) & 0xFF)
#define SPI_RDY                                 (1 << 30)

#define SPI_FIFO_STATUS                         0x014
#define SPI_RX_FIFO_EMPTY                       (1 << 0)
#define SPI_RX_FIFO_FULL                        (1 << 1)
#define SPI_TX_FIFO_EMPTY                       (1 << 2)
#define SPI_TX_FIFO_FULL                        (1 << 3)
#define SPI_RX_FIFO_UNF                         (1 << 4)
#define SPI_RX_FIFO_OVF                         (1 << 5)
#define SPI_TX_FIFO_UNF                         (1 << 6)
#define SPI_TX_FIFO_OVF                         (1 << 7)
#define SPI_ERR                                 (1 << 8)
#define SPI_TX_FIFO_FLUSH                       (1 << 14)
#define SPI_RX_FIFO_FLUSH                       (1 << 15)
#define SPI_TX_FIFO_EMPTY_COUNT(val)            (((val) >> 16) & 0x7F)
#define SPI_RX_FIFO_FULL_COUNT(val)             (((val) >> 23) & 0x7F)
#define SPI_FRAME_END                           (1 << 30)
#define SPI_CS_INACTIVE                         (1 << 31)

#define SPI_FIFO_ERROR                          (SPI_RX_FIFO_UNF | \
                        SPI_RX_FIFO_OVF | SPI_TX_FIFO_UNF | SPI_TX_FIFO_OVF)
#define SPI_FIFO_EMPTY                  (SPI_RX_FIFO_EMPTY | SPI_TX_FIFO_EMPTY)

#define SPI_TX_DATA                             0x018
#define SPI_RX_DATA                             0x01C

#define SPI_DMA_CTL                             0x020
#define SPI_TX_TRIG_1                           (0 << 15)
#define SPI_TX_TRIG_4                           (1 << 15)
#define SPI_TX_TRIG_8                           (2 << 15)
#define SPI_TX_TRIG_16                          (3 << 15)
#define SPI_TX_TRIG_MASK                        (3 << 15)
#define SPI_RX_TRIG_1                           (0 << 19)
#define SPI_RX_TRIG_4                           (1 << 19)
#define SPI_RX_TRIG_8                           (2 << 19)
#define SPI_RX_TRIG_16                          (3 << 19)
#define SPI_RX_TRIG_MASK                        (3 << 19)
#define SPI_IE_TX                               (1 << 28)
#define SPI_IE_RX                               (1 << 29)
#define SPI_CONT                                (1 << 30)
#define SPI_DMA                                 (1 << 31)
#define SPI_DMA_EN                              SPI_DMA

#define SPI_DMA_BLK                             0x024
#define SPI_DMA_BLK_SET(x)                      (((x) & 0xFFFF) << 0)

#define SPI_TX_FIFO                             0x108
#define SPI_RX_FIFO                             0x188
#define MAX_CHIP_SELECT                         4
#define SPI_FIFO_DEPTH                          64
#define DATA_DIR_TX                             (1 << 0)
#define DATA_DIR_RX                             (1 << 1)

#define SPI_DMA_TIMEOUT                         (msecs_to_jiffies(1000))
#define DEFAULT_SPI_DMA_BUF_LEN                 (16*1024)
#define TX_FIFO_EMPTY_COUNT_MAX                 SPI_TX_FIFO_EMPTY_COUNT(0x40)
#define RX_FIFO_FULL_COUNT_ZERO                 SPI_RX_FIFO_FULL_COUNT(0)
#define MAX_HOLD_CYCLES                         16
#define SPI_DEFAULT_SPEED                       25000000

struct tegra_spi_data {
        struct device                           *dev;
        struct spi_master                       *master;
        spinlock_t                              lock;

        struct clk                              *clk;
        struct reset_control                    *rst;
        void __iomem                            *base;
        phys_addr_t                             phys;
        unsigned                                irq;
        u32                                     cur_speed;

        struct spi_device                       *cur_spi;
        struct spi_device                       *cs_control;
        unsigned                                cur_pos;
        unsigned                                words_per_32bit;
        unsigned                                bytes_per_word;
        unsigned                                curr_dma_words;
        unsigned                                cur_direction;

        unsigned                                cur_rx_pos;
        unsigned                                cur_tx_pos;

        unsigned                                dma_buf_size;
        unsigned                                max_buf_size;
        bool                                    is_curr_dma_xfer;

        struct completion                       rx_dma_complete;
        struct completion                       tx_dma_complete;

        u32                                     tx_status;
        u32                                     rx_status;
        u32                                     status_reg;
        bool                                    is_packed;

        u32                                     command1_reg;
        u32                                     dma_control_reg;
        u32                                     def_command1_reg;

        struct completion                       xfer_completion;
        struct spi_transfer                     *curr_xfer;
        struct dma_chan                         *rx_dma_chan;
        u32                                     *rx_dma_buf;
        dma_addr_t                              rx_dma_phys;
        struct dma_async_tx_descriptor          *rx_dma_desc;

        struct dma_chan                         *tx_dma_chan;
        u32                                     *tx_dma_buf;
        dma_addr_t                              tx_dma_phys;
        struct dma_async_tx_descriptor          *tx_dma_desc;
};

static int tegra_spi_runtime_suspend(struct device *dev);
static int tegra_spi_runtime_resume(struct device *dev);

static inline u32 tegra_spi_readl(struct tegra_spi_data *tspi,
                unsigned long reg)
{
        return readl(tspi->base + reg);
}

static inline void tegra_spi_writel(struct tegra_spi_data *tspi,
                u32 val, unsigned long reg)
{
        writel(val, tspi->base + reg);

        /* Read back register to make sure that register writes completed */
        if (reg != SPI_TX_FIFO)
                readl(tspi->base + SPI_COMMAND1);
}

static void tegra_spi_clear_status(struct tegra_spi_data *tspi)
{
        u32 val;

        /* Write 1 to clear status register */
        val = tegra_spi_readl(tspi, SPI_TRANS_STATUS);
        tegra_spi_writel(tspi, val, SPI_TRANS_STATUS);

        /* Clear fifo status error if any */
        val = tegra_spi_readl(tspi, SPI_FIFO_STATUS);
        if (val & SPI_ERR)
                tegra_spi_writel(tspi, SPI_ERR | SPI_FIFO_ERROR,
                                SPI_FIFO_STATUS);
}

static unsigned tegra_spi_calculate_curr_xfer_param(
        struct spi_device *spi, struct tegra_spi_data *tspi,
        struct spi_transfer *t)
{
        unsigned remain_len = t->len - tspi->cur_pos;
        unsigned max_word;
        unsigned bits_per_word = t->bits_per_word;
        unsigned max_len;
        unsigned total_fifo_words;

        tspi->bytes_per_word = DIV_ROUND_UP(bits_per_word, 8);

        if (bits_per_word == 8 || bits_per_word == 16) {
                tspi->is_packed = 1;
                tspi->words_per_32bit = 32/bits_per_word;
        } else {
                tspi->is_packed = 0;
                tspi->words_per_32bit = 1;
        }

        if (tspi->is_packed) {
                max_len = min(remain_len, tspi->max_buf_size);
                tspi->curr_dma_words = max_len/tspi->bytes_per_word;
                total_fifo_words = (max_len + 3) / 4;
        } else {
                max_word = (remain_len - 1) / tspi->bytes_per_word + 1;
                max_word = min(max_word, tspi->max_buf_size/4);
                tspi->curr_dma_words = max_word;
                total_fifo_words = max_word;
        }
        return total_fifo_words;
}

static unsigned tegra_spi_fill_tx_fifo_from_client_txbuf(
        struct tegra_spi_data *tspi, struct spi_transfer *t)
{
        unsigned nbytes;
        unsigned tx_empty_count;
        u32 fifo_status;
        unsigned max_n_32bit;
        unsigned i, count;
        unsigned int written_words;
        unsigned fifo_words_left;
        u8 *tx_buf = (u8 *)t->tx_buf + tspi->cur_tx_pos;

        fifo_status = tegra_spi_readl(tspi, SPI_FIFO_STATUS);
        tx_empty_count = SPI_TX_FIFO_EMPTY_COUNT(fifo_status);

        if (tspi->is_packed) {
                fifo_words_left = tx_empty_count * tspi->words_per_32bit;
                written_words = min(fifo_words_left, tspi->curr_dma_words);
                nbytes = written_words * tspi->bytes_per_word;
                max_n_32bit = DIV_ROUND_UP(nbytes, 4);
                for (count = 0; count < max_n_32bit; count++) {
                        u32 x = 0;

                        for (i = 0; (i < 4) && nbytes; i++, nbytes--)
                                x |= (u32)(*tx_buf++) << (i * 8);
                        tegra_spi_writel(tspi, x, SPI_TX_FIFO);
                }

                tspi->cur_tx_pos += written_words * tspi->bytes_per_word;
        } else {
                unsigned int write_bytes;
                max_n_32bit = min(tspi->curr_dma_words,  tx_empty_count);
                written_words = max_n_32bit;
                nbytes = written_words * tspi->bytes_per_word;
                if (nbytes > t->len - tspi->cur_pos)
                        nbytes = t->len - tspi->cur_pos;
                write_bytes = nbytes;
                for (count = 0; count < max_n_32bit; count++) {
                        u32 x = 0;

                        for (i = 0; nbytes && (i < tspi->bytes_per_word);
                                                        i++, nbytes--)
                                x |= (u32)(*tx_buf++) << (i * 8);
                        tegra_spi_writel(tspi, x, SPI_TX_FIFO);
                }

                tspi->cur_tx_pos += write_bytes;
        }

        return written_words;
}

static unsigned int tegra_spi_read_rx_fifo_to_client_rxbuf(
                struct tegra_spi_data *tspi, struct spi_transfer *t)
{
        unsigned rx_full_count;
        u32 fifo_status;
        unsigned i, count;
        unsigned int read_words = 0;
        unsigned len;
        u8 *rx_buf = (u8 *)t->rx_buf + tspi->cur_rx_pos;

        fifo_status = tegra_spi_readl(tspi, SPI_FIFO_STATUS);
        rx_full_count = SPI_RX_FIFO_FULL_COUNT(fifo_status);
        if (tspi->is_packed) {
                len = tspi->curr_dma_words * tspi->bytes_per_word;
                for (count = 0; count < rx_full_count; count++) {
                        u32 x = tegra_spi_readl(tspi, SPI_RX_FIFO);

                        for (i = 0; len && (i < 4); i++, len--)
                                *rx_buf++ = (x >> i*8) & 0xFF;
                }
                read_words += tspi->curr_dma_words;
                tspi->cur_rx_pos += tspi->curr_dma_words * tspi->bytes_per_word;
        } else {
                u32 rx_mask = ((u32)1 << t->bits_per_word) - 1;
                u8 bytes_per_word = tspi->bytes_per_word;
                unsigned int read_bytes;

                len = rx_full_count * bytes_per_word;
                if (len > t->len - tspi->cur_pos)
                        len = t->len - tspi->cur_pos;
                read_bytes = len;
                for (count = 0; count < rx_full_count; count++) {
                        u32 x = tegra_spi_readl(tspi, SPI_RX_FIFO) & rx_mask;

                        for (i = 0; len && (i < bytes_per_word); i++, len--)
                                *rx_buf++ = (x >> (i*8)) & 0xFF;
                }
                read_words += rx_full_count;
                tspi->cur_rx_pos += read_bytes;
        }

        return read_words;
}

static void tegra_spi_copy_client_txbuf_to_spi_txbuf(
                struct tegra_spi_data *tspi, struct spi_transfer *t)
{
        /* Make the dma buffer to read by cpu */
        dma_sync_single_for_cpu(tspi->dev, tspi->tx_dma_phys,
                                tspi->dma_buf_size, DMA_TO_DEVICE);

        if (tspi->is_packed) {
                unsigned len = tspi->curr_dma_words * tspi->bytes_per_word;

                memcpy(tspi->tx_dma_buf, t->tx_buf + tspi->cur_pos, len);
                tspi->cur_tx_pos += tspi->curr_dma_words * tspi->bytes_per_word;
        } else {
                unsigned int i;
                unsigned int count;
                u8 *tx_buf = (u8 *)t->tx_buf + tspi->cur_tx_pos;
                unsigned consume = tspi->curr_dma_words * tspi->bytes_per_word;
                unsigned int write_bytes;

                if (consume > t->len - tspi->cur_pos)
                        consume = t->len - tspi->cur_pos;
                write_bytes = consume;
                for (count = 0; count < tspi->curr_dma_words; count++) {
                        u32 x = 0;

                        for (i = 0; consume && (i < tspi->bytes_per_word);
                                                        i++, consume--)
                                x |= (u32)(*tx_buf++) << (i * 8);
                        tspi->tx_dma_buf[count] = x;
                }

                tspi->cur_tx_pos += write_bytes;
        }

        /* Make the dma buffer to read by dma */
        dma_sync_single_for_device(tspi->dev, tspi->tx_dma_phys,
                                tspi->dma_buf_size, DMA_TO_DEVICE);
}

static void tegra_spi_copy_spi_rxbuf_to_client_rxbuf(
                struct tegra_spi_data *tspi, struct spi_transfer *t)
{
        /* Make the dma buffer to read by cpu */
        dma_sync_single_for_cpu(tspi->dev, tspi->rx_dma_phys,
                tspi->dma_buf_size, DMA_FROM_DEVICE);

        if (tspi->is_packed) {
                unsigned len = tspi->curr_dma_words * tspi->bytes_per_word;

                memcpy(t->rx_buf + tspi->cur_rx_pos, tspi->rx_dma_buf, len);
                tspi->cur_rx_pos += tspi->curr_dma_words * tspi->bytes_per_word;
        } else {
                unsigned int i;
                unsigned int count;
                unsigned char *rx_buf = t->rx_buf + tspi->cur_rx_pos;
                u32 rx_mask = ((u32)1 << t->bits_per_word) - 1;
                unsigned consume = tspi->curr_dma_words * tspi->bytes_per_word;
                unsigned int read_bytes;

                if (consume > t->len - tspi->cur_pos)
                        consume = t->len - tspi->cur_pos;
                read_bytes = consume;
                for (count = 0; count < tspi->curr_dma_words; count++) {
                        u32 x = tspi->rx_dma_buf[count] & rx_mask;

                        for (i = 0; consume && (i < tspi->bytes_per_word);
                                                        i++, consume--)
                                *rx_buf++ = (x >> (i*8)) & 0xFF;
                }

                tspi->cur_rx_pos += read_bytes;
        }

        /* Make the dma buffer to read by dma */
        dma_sync_single_for_device(tspi->dev, tspi->rx_dma_phys,
                tspi->dma_buf_size, DMA_FROM_DEVICE);
}

static void tegra_spi_dma_complete(void *args)
{
        struct completion *dma_complete = args;

        complete(dma_complete);
}

static int tegra_spi_start_tx_dma(struct tegra_spi_data *tspi, int len)
{
        reinit_completion(&tspi->tx_dma_complete);
        tspi->tx_dma_desc = dmaengine_prep_slave_single(tspi->tx_dma_chan,
                                tspi->tx_dma_phys, len, DMA_MEM_TO_DEV,
                                DMA_PREP_INTERRUPT |  DMA_CTRL_ACK);
        if (!tspi->tx_dma_desc) {
                dev_err(tspi->dev, "Not able to get desc for Tx\n");
                return -EIO;
        }

        tspi->tx_dma_desc->callback = tegra_spi_dma_complete;
        tspi->tx_dma_desc->callback_param = &tspi->tx_dma_complete;

        dmaengine_submit(tspi->tx_dma_desc);
        dma_async_issue_pending(tspi->tx_dma_chan);
        return 0;
}

static int tegra_spi_start_rx_dma(struct tegra_spi_data *tspi, int len)
{
        reinit_completion(&tspi->rx_dma_complete);
        tspi->rx_dma_desc = dmaengine_prep_slave_single(tspi->rx_dma_chan,
                                tspi->rx_dma_phys, len, DMA_DEV_TO_MEM,
                                DMA_PREP_INTERRUPT |  DMA_CTRL_ACK);
        if (!tspi->rx_dma_desc) {
                dev_err(tspi->dev, "Not able to get desc for Rx\n");
                return -EIO;
        }

        tspi->rx_dma_desc->callback = tegra_spi_dma_complete;
        tspi->rx_dma_desc->callback_param = &tspi->rx_dma_complete;

        dmaengine_submit(tspi->rx_dma_desc);
        dma_async_issue_pending(tspi->rx_dma_chan);
        return 0;
}

static int tegra_spi_flush_fifos(struct tegra_spi_data *tspi)
{
        unsigned long timeout = jiffies + HZ;
        u32 status;

        status = tegra_spi_readl(tspi, SPI_FIFO_STATUS);
        if ((status & SPI_FIFO_EMPTY) != SPI_FIFO_EMPTY) {
                status |= SPI_RX_FIFO_FLUSH | SPI_TX_FIFO_FLUSH;
                tegra_spi_writel(tspi, status, SPI_FIFO_STATUS);
                while ((status & SPI_FIFO_EMPTY) != SPI_FIFO_EMPTY) {
                        status = tegra_spi_readl(tspi, SPI_FIFO_STATUS);
                        if (time_after(jiffies, timeout)) {
                                dev_err(tspi->dev,
                                        "timeout waiting for fifo flush\n");
                                return -EIO;
                        }

                        udelay(1);
                }
        }

        return 0;
}

static int tegra_spi_start_dma_based_transfer(
                struct tegra_spi_data *tspi, struct spi_transfer *t)
{
        u32 val;
        unsigned int len;
        int ret = 0;

        val = SPI_DMA_BLK_SET(tspi->curr_dma_words - 1);
        tegra_spi_writel(tspi, val, SPI_DMA_BLK);

        if (tspi->is_packed)
                len = DIV_ROUND_UP(tspi->curr_dma_words * tspi->bytes_per_word,
                                        4) * 4;
        else
                len = tspi->curr_dma_words * 4;

        /* Set attention level based on length of transfer */
        if (len & 0xF)
                val |= SPI_TX_TRIG_1 | SPI_RX_TRIG_1;
        else if (((len) >> 4) & 0x1)
                val |= SPI_TX_TRIG_4 | SPI_RX_TRIG_4;
        else
                val |= SPI_TX_TRIG_8 | SPI_RX_TRIG_8;

        if (tspi->cur_direction & DATA_DIR_TX)
                val |= SPI_IE_TX;

        if (tspi->cur_direction & DATA_DIR_RX)
                val |= SPI_IE_RX;

        tegra_spi_writel(tspi, val, SPI_DMA_CTL);
        tspi->dma_control_reg = val;

        if (tspi->cur_direction & DATA_DIR_TX) {
                tegra_spi_copy_client_txbuf_to_spi_txbuf(tspi, t);
                ret = tegra_spi_start_tx_dma(tspi, len);
                if (ret < 0) {
                        dev_err(tspi->dev,
                                "Starting tx dma failed, err %d\n", ret);
                        return ret;
                }
        }

        if (tspi->cur_direction & DATA_DIR_RX) {
                /* Make the dma buffer to read by dma */
                dma_sync_single_for_device(tspi->dev, tspi->rx_dma_phys,
                                tspi->dma_buf_size, DMA_FROM_DEVICE);

                ret = tegra_spi_start_rx_dma(tspi, len);
                if (ret < 0) {
                        dev_err(tspi->dev,
                                "Starting rx dma failed, err %d\n", ret);
                        if (tspi->cur_direction & DATA_DIR_TX)
                                dmaengine_terminate_all(tspi->tx_dma_chan);
                        return ret;
                }
        }
        tspi->is_curr_dma_xfer = true;
        tspi->dma_control_reg = val;

        val |= SPI_DMA_EN;
        tegra_spi_writel(tspi, val, SPI_DMA_CTL);
        return ret;
}

static int tegra_spi_start_cpu_based_transfer(
                struct tegra_spi_data *tspi, struct spi_transfer *t)
{
        u32 val;
        unsigned cur_words;

        if (tspi->cur_direction & DATA_DIR_TX)
                cur_words = tegra_spi_fill_tx_fifo_from_client_txbuf(tspi, t);
        else
                cur_words = tspi->curr_dma_words;

        val = SPI_DMA_BLK_SET(cur_words - 1);
        tegra_spi_writel(tspi, val, SPI_DMA_BLK);

        val = 0;
        if (tspi->cur_direction & DATA_DIR_TX)
                val |= SPI_IE_TX;

        if (tspi->cur_direction & DATA_DIR_RX)
                val |= SPI_IE_RX;

        tegra_spi_writel(tspi, val, SPI_DMA_CTL);
        tspi->dma_control_reg = val;

        tspi->is_curr_dma_xfer = false;

        val |= SPI_DMA_EN;
        tegra_spi_writel(tspi, val, SPI_DMA_CTL);
        return 0;
}

static int tegra_spi_init_dma_param(struct tegra_spi_data *tspi,
                        bool dma_to_memory)
{
        struct dma_chan *dma_chan;
        u32 *dma_buf;
        dma_addr_t dma_phys;
        int ret;
        struct dma_slave_config dma_sconfig;

        dma_chan = dma_request_slave_channel_reason(tspi->dev,
                                        dma_to_memory ? "rx" : "tx");
        if (IS_ERR(dma_chan)) {
                ret = PTR_ERR(dma_chan);
                if (ret != -EPROBE_DEFER)
                        dev_err(tspi->dev,
                                "Dma channel is not available: %d\n", ret);
                return ret;
        }

        dma_buf = dma_alloc_coherent(tspi->dev, tspi->dma_buf_size,
                                &dma_phys, GFP_KERNEL);
        if (!dma_buf) {
                dev_err(tspi->dev, " Not able to allocate the dma buffer\n");
                dma_release_channel(dma_chan);
                return -ENOMEM;
        }

        if (dma_to_memory) {
                dma_sconfig.src_addr = tspi->phys + SPI_RX_FIFO;
                dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
                dma_sconfig.src_maxburst = 0;
        } else {
                dma_sconfig.dst_addr = tspi->phys + SPI_TX_FIFO;
                dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
                dma_sconfig.dst_maxburst = 0;
        }

        ret = dmaengine_slave_config(dma_chan, &dma_sconfig);
        if (ret)
                goto scrub;
        if (dma_to_memory) {
                tspi->rx_dma_chan = dma_chan;
                tspi->rx_dma_buf = dma_buf;
                tspi->rx_dma_phys = dma_phys;
        } else {
                tspi->tx_dma_chan = dma_chan;
                tspi->tx_dma_buf = dma_buf;
                tspi->tx_dma_phys = dma_phys;
        }
        return 0;

scrub:
        dma_free_coherent(tspi->dev, tspi->dma_buf_size, dma_buf, dma_phys);
        dma_release_channel(dma_chan);
        return ret;
}

static void tegra_spi_deinit_dma_param(struct tegra_spi_data *tspi,
        bool dma_to_memory)
{
        u32 *dma_buf;
        dma_addr_t dma_phys;
        struct dma_chan *dma_chan;

        if (dma_to_memory) {
                dma_buf = tspi->rx_dma_buf;
                dma_chan = tspi->rx_dma_chan;
                dma_phys = tspi->rx_dma_phys;
                tspi->rx_dma_chan = NULL;
                tspi->rx_dma_buf = NULL;
        } else {
                dma_buf = tspi->tx_dma_buf;
                dma_chan = tspi->tx_dma_chan;
                dma_phys = tspi->tx_dma_phys;
                tspi->tx_dma_buf = NULL;
                tspi->tx_dma_chan = NULL;
        }
        if (!dma_chan)
                return;

        dma_free_coherent(tspi->dev, tspi->dma_buf_size, dma_buf, dma_phys);
        dma_release_channel(dma_chan);
}

static u32 tegra_spi_setup_transfer_one(struct spi_device *spi,
                struct spi_transfer *t, bool is_first_of_msg)
{
        struct tegra_spi_data *tspi = spi_master_get_devdata(spi->master);
        u32 speed = t->speed_hz;
        u8 bits_per_word = t->bits_per_word;
        u32 command1;
        int req_mode;

        if (speed != tspi->cur_speed) {
                clk_set_rate(tspi->clk, speed);
                tspi->cur_speed = speed;
        }

        tspi->cur_spi = spi;
        tspi->cur_pos = 0;
        tspi->cur_rx_pos = 0;
        tspi->cur_tx_pos = 0;
        tspi->curr_xfer = t;

        if (is_first_of_msg) {
                tegra_spi_clear_status(tspi);

                command1 = tspi->def_command1_reg;
                command1 |= SPI_BIT_LENGTH(bits_per_word - 1);

                command1 &= ~SPI_CONTROL_MODE_MASK;
                req_mode = spi->mode & 0x3;
                if (req_mode == SPI_MODE_0)
                        command1 |= SPI_CONTROL_MODE_0;
                else if (req_mode == SPI_MODE_1)
                        command1 |= SPI_CONTROL_MODE_1;
                else if (req_mode == SPI_MODE_2)
                        command1 |= SPI_CONTROL_MODE_2;
                else if (req_mode == SPI_MODE_3)
                        command1 |= SPI_CONTROL_MODE_3;

                if (tspi->cs_control) {
                        if (tspi->cs_control != spi)
                                tegra_spi_writel(tspi, command1, SPI_COMMAND1);
                        tspi->cs_control = NULL;
                } else
                        tegra_spi_writel(tspi, command1, SPI_COMMAND1);

                command1 |= SPI_CS_SW_HW;
                if (spi->mode & SPI_CS_HIGH)
                        command1 |= SPI_CS_SW_VAL;
                else
                        command1 &= ~SPI_CS_SW_VAL;

                tegra_spi_writel(tspi, 0, SPI_COMMAND2);
        } else {
                command1 = tspi->command1_reg;
                command1 &= ~SPI_BIT_LENGTH(~0);
                command1 |= SPI_BIT_LENGTH(bits_per_word - 1);
        }

        return command1;
}

static int tegra_spi_start_transfer_one(struct spi_device *spi,
                struct spi_transfer *t, u32 command1)
{
        struct tegra_spi_data *tspi = spi_master_get_devdata(spi->master);
        unsigned total_fifo_words;
        int ret;

        total_fifo_words = tegra_spi_calculate_curr_xfer_param(spi, tspi, t);

        if (tspi->is_packed)
                command1 |= SPI_PACKED;
        else
                command1 &= ~SPI_PACKED;

        command1 &= ~(SPI_CS_SEL_MASK | SPI_TX_EN | SPI_RX_EN);
        tspi->cur_direction = 0;
        if (t->rx_buf) {
                command1 |= SPI_RX_EN;
                tspi->cur_direction |= DATA_DIR_RX;
        }
        if (t->tx_buf) {
                command1 |= SPI_TX_EN;
                tspi->cur_direction |= DATA_DIR_TX;
        }
        command1 |= SPI_CS_SEL(spi->chip_select);
        tegra_spi_writel(tspi, command1, SPI_COMMAND1);
        tspi->command1_reg = command1;

        dev_dbg(tspi->dev, "The def 0x%x and written 0x%x\n",
                tspi->def_command1_reg, (unsigned)command1);

        ret = tegra_spi_flush_fifos(tspi);
        if (ret < 0)
                return ret;
        if (total_fifo_words > SPI_FIFO_DEPTH)
                ret = tegra_spi_start_dma_based_transfer(tspi, t);
        else
                ret = tegra_spi_start_cpu_based_transfer(tspi, t);
        return ret;
}

static int tegra_spi_setup(struct spi_device *spi)
{
        struct tegra_spi_data *tspi = spi_master_get_devdata(spi->master);
        u32 val;
        unsigned long flags;
        int ret;

        dev_dbg(&spi->dev, "setup %d bpw, %scpol, %scpha, %dHz\n",
                spi->bits_per_word,
                spi->mode & SPI_CPOL ? "" : "~",
                spi->mode & SPI_CPHA ? "" : "~",
                spi->max_speed_hz);

        ret = pm_runtime_get_sync(tspi->dev);
        if (ret < 0) {
                dev_err(tspi->dev, "pm runtime failed, e = %d\n", ret);
                return ret;
        }

        spin_lock_irqsave(&tspi->lock, flags);
        val = tspi->def_command1_reg;
        if (spi->mode & SPI_CS_HIGH)
                val &= ~SPI_CS_POL_INACTIVE(spi->chip_select);
        else
                val |= SPI_CS_POL_INACTIVE(spi->chip_select);
        tspi->def_command1_reg = val;
        tegra_spi_writel(tspi, tspi->def_command1_reg, SPI_COMMAND1);
        spin_unlock_irqrestore(&tspi->lock, flags);

        pm_runtime_put(tspi->dev);
        return 0;
}

static void tegra_spi_transfer_delay(int delay)
{
        if (!delay)
                return;

        if (delay >= 1000)
                mdelay(delay / 1000);

        udelay(delay % 1000);
}

static int tegra_spi_transfer_one_message(struct spi_master *master,
                        struct spi_message *msg)
{
        bool is_first_msg = true;
        struct tegra_spi_data *tspi = spi_master_get_devdata(master);
        struct spi_transfer *xfer;
        struct spi_device *spi = msg->spi;
        int ret;
        bool skip = false;

        msg->status = 0;
        msg->actual_length = 0;

        list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                u32 cmd1;

                reinit_completion(&tspi->xfer_completion);

                cmd1 = tegra_spi_setup_transfer_one(spi, xfer, is_first_msg);

                if (!xfer->len) {
                        ret = 0;
                        skip = true;
                        goto complete_xfer;
                }

                ret = tegra_spi_start_transfer_one(spi, xfer, cmd1);
                if (ret < 0) {
                        dev_err(tspi->dev,
                                "spi can not start transfer, err %d\n", ret);
                        goto complete_xfer;
                }

                is_first_msg = false;
                ret = wait_for_completion_timeout(&tspi->xfer_completion,
                                                SPI_DMA_TIMEOUT);
                if (WARN_ON(ret == 0)) {
                        dev_err(tspi->dev,
                                "spi transfer timeout, err %d\n", ret);
                        if (tspi->is_curr_dma_xfer &&
                            (tspi->cur_direction & DATA_DIR_TX))
                                dmaengine_terminate_all(tspi->tx_dma_chan);
                        if (tspi->is_curr_dma_xfer &&
                            (tspi->cur_direction & DATA_DIR_RX))
                                dmaengine_terminate_all(tspi->rx_dma_chan);
                        ret = -EIO;
                        tegra_spi_flush_fifos(tspi);
                        reset_control_assert(tspi->rst);
                        udelay(2);
                        reset_control_deassert(tspi->rst);
                        goto complete_xfer;
                }

                if (tspi->tx_status ||  tspi->rx_status) {
                        dev_err(tspi->dev, "Error in Transfer\n");
                        ret = -EIO;
                        goto complete_xfer;
                }
                msg->actual_length += xfer->len;

complete_xfer:
                if (ret < 0 || skip) {
                        tegra_spi_writel(tspi, tspi->def_command1_reg,
                                        SPI_COMMAND1);
                        tegra_spi_transfer_delay(xfer->delay_usecs);
                        goto exit;
                } else if (list_is_last(&xfer->transfer_list,
                                        &msg->transfers)) {
                        if (xfer->cs_change)
                                tspi->cs_control = spi;
                        else {
                                tegra_spi_writel(tspi, tspi->def_command1_reg,
                                                SPI_COMMAND1);
                                tegra_spi_transfer_delay(xfer->delay_usecs);
                        }
                } else if (xfer->cs_change) {
                        tegra_spi_writel(tspi, tspi->def_command1_reg,
                                        SPI_COMMAND1);
                        tegra_spi_transfer_delay(xfer->delay_usecs);
                }

        }
        ret = 0;
exit:
        msg->status = ret;
        spi_finalize_current_message(master);
        return ret;
}

static irqreturn_t handle_cpu_based_xfer(struct tegra_spi_data *tspi)
{
        struct spi_transfer *t = tspi->curr_xfer;
        unsigned long flags;

        spin_lock_irqsave(&tspi->lock, flags);
        if (tspi->tx_status ||  tspi->rx_status) {
                dev_err(tspi->dev, "CpuXfer ERROR bit set 0x%x\n",
                        tspi->status_reg);
                dev_err(tspi->dev, "CpuXfer 0x%08x:0x%08x\n",
                        tspi->command1_reg, tspi->dma_control_reg);
                tegra_spi_flush_fifos(tspi);
                reset_control_assert(tspi->rst);
                udelay(2);
                reset_control_deassert(tspi->rst);
                complete(&tspi->xfer_completion);
                goto exit;
        }

        if (tspi->cur_direction & DATA_DIR_RX)
                tegra_spi_read_rx_fifo_to_client_rxbuf(tspi, t);

        if (tspi->cur_direction & DATA_DIR_TX)
                tspi->cur_pos = tspi->cur_tx_pos;
        else
                tspi->cur_pos = tspi->cur_rx_pos;

        if (tspi->cur_pos == t->len) {
                complete(&tspi->xfer_completion);
                goto exit;
        }

        tegra_spi_calculate_curr_xfer_param(tspi->cur_spi, tspi, t);
        tegra_spi_start_cpu_based_transfer(tspi, t);
exit:
        spin_unlock_irqrestore(&tspi->lock, flags);
        return IRQ_HANDLED;
}

static irqreturn_t handle_dma_based_xfer(struct tegra_spi_data *tspi)
{
        struct spi_transfer *t = tspi->curr_xfer;
        long wait_status;
        int err = 0;
        unsigned total_fifo_words;
        unsigned long flags;

        /* Abort dmas if any error */
        if (tspi->cur_direction & DATA_DIR_TX) {
                if (tspi->tx_status) {
                        dmaengine_terminate_all(tspi->tx_dma_chan);
                        err += 1;
                } else {
                        wait_status = wait_for_completion_interruptible_timeout(
                                &tspi->tx_dma_complete, SPI_DMA_TIMEOUT);
                        if (wait_status <= 0) {
                                dmaengine_terminate_all(tspi->tx_dma_chan);
                                dev_err(tspi->dev, "TxDma Xfer failed\n");
                                err += 1;
                        }
                }
        }

        if (tspi->cur_direction & DATA_DIR_RX) {
                if (tspi->rx_status) {
                        dmaengine_terminate_all(tspi->rx_dma_chan);
                        err += 2;
                } else {
                        wait_status = wait_for_completion_interruptible_timeout(
                                &tspi->rx_dma_complete, SPI_DMA_TIMEOUT);
                        if (wait_status <= 0) {
                                dmaengine_terminate_all(tspi->rx_dma_chan);
                                dev_err(tspi->dev, "RxDma Xfer failed\n");
                                err += 2;
                        }
                }
        }

        spin_lock_irqsave(&tspi->lock, flags);
        if (err) {
                dev_err(tspi->dev, "DmaXfer: ERROR bit set 0x%x\n",
                        tspi->status_reg);
                dev_err(tspi->dev, "DmaXfer 0x%08x:0x%08x\n",
                        tspi->command1_reg, tspi->dma_control_reg);
                tegra_spi_flush_fifos(tspi);
                reset_control_assert(tspi->rst);
                udelay(2);
                reset_control_deassert(tspi->rst);
                complete(&tspi->xfer_completion);
                spin_unlock_irqrestore(&tspi->lock, flags);
                return IRQ_HANDLED;
        }

        if (tspi->cur_direction & DATA_DIR_RX)
                tegra_spi_copy_spi_rxbuf_to_client_rxbuf(tspi, t);

        if (tspi->cur_direction & DATA_DIR_TX)
                tspi->cur_pos = tspi->cur_tx_pos;
        else
                tspi->cur_pos = tspi->cur_rx_pos;

        if (tspi->cur_pos == t->len) {
                complete(&tspi->xfer_completion);
                goto exit;
        }

        /* Continue transfer in current message */
        total_fifo_words = tegra_spi_calculate_curr_xfer_param(tspi->cur_spi,
                                                        tspi, t);
        if (total_fifo_words > SPI_FIFO_DEPTH)
                err = tegra_spi_start_dma_based_transfer(tspi, t);
        else
                err = tegra_spi_start_cpu_based_transfer(tspi, t);

exit:
        spin_unlock_irqrestore(&tspi->lock, flags);
        return IRQ_HANDLED;
}

static irqreturn_t tegra_spi_isr_thread(int irq, void *context_data)
{
        struct tegra_spi_data *tspi = context_data;

        if (!tspi->is_curr_dma_xfer)
                return handle_cpu_based_xfer(tspi);
        return handle_dma_based_xfer(tspi);
}

static irqreturn_t tegra_spi_isr(int irq, void *context_data)
{
        struct tegra_spi_data *tspi = context_data;

        tspi->status_reg = tegra_spi_readl(tspi, SPI_FIFO_STATUS);
        if (tspi->cur_direction & DATA_DIR_TX)
                tspi->tx_status = tspi->status_reg &
                                        (SPI_TX_FIFO_UNF | SPI_TX_FIFO_OVF);

        if (tspi->cur_direction & DATA_DIR_RX)
                tspi->rx_status = tspi->status_reg &
                                        (SPI_RX_FIFO_OVF | SPI_RX_FIFO_UNF);
        tegra_spi_clear_status(tspi);

        return IRQ_WAKE_THREAD;
}

static const struct of_device_id tegra_spi_of_match[] = {
        { .compatible = "nvidia,tegra114-spi", },
        {}
};
MODULE_DEVICE_TABLE(of, tegra_spi_of_match);

static int tegra_spi_probe(struct platform_device *pdev)
{
        struct spi_master       *master;
        struct tegra_spi_data   *tspi;
        struct resource         *r;
        int ret, spi_irq;

        master = spi_alloc_master(&pdev->dev, sizeof(*tspi));
        if (!master) {
                dev_err(&pdev->dev, "master allocation failed\n");
                return -ENOMEM;
        }
        platform_set_drvdata(pdev, master);
        tspi = spi_master_get_devdata(master);

        if (of_property_read_u32(pdev->dev.of_node, "spi-max-frequency",
                                 &master->max_speed_hz))
                master->max_speed_hz = 25000000; /* 25MHz */

        /* the spi->mode bits understood by this driver: */
        master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
        master->setup = tegra_spi_setup;
        master->transfer_one_message = tegra_spi_transfer_one_message;
        master->num_chipselect = MAX_CHIP_SELECT;
        master->auto_runtime_pm = true;

        tspi->master = master;
        tspi->dev = &pdev->dev;
        spin_lock_init(&tspi->lock);

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        tspi->base = devm_ioremap_resource(&pdev->dev, r);
        if (IS_ERR(tspi->base)) {
                ret = PTR_ERR(tspi->base);
                goto exit_free_master;
        }
        tspi->phys = r->start;

        spi_irq = platform_get_irq(pdev, 0);
        tspi->irq = spi_irq;

        tspi->clk = devm_clk_get(&pdev->dev, "spi");
        if (IS_ERR(tspi->clk)) {
                dev_err(&pdev->dev, "can not get clock\n");
                ret = PTR_ERR(tspi->clk);
                goto exit_free_master;
        }

        tspi->rst = devm_reset_control_get_exclusive(&pdev->dev, "spi");
        if (IS_ERR(tspi->rst)) {
                dev_err(&pdev->dev, "can not get reset\n");
                ret = PTR_ERR(tspi->rst);
                goto exit_free_master;
        }

        tspi->max_buf_size = SPI_FIFO_DEPTH << 2;
        tspi->dma_buf_size = DEFAULT_SPI_DMA_BUF_LEN;

        ret = tegra_spi_init_dma_param(tspi, true);
        if (ret < 0)
                goto exit_free_master;
        ret = tegra_spi_init_dma_param(tspi, false);
        if (ret < 0)
                goto exit_rx_dma_free;
        tspi->max_buf_size = tspi->dma_buf_size;
        init_completion(&tspi->tx_dma_complete);
        init_completion(&tspi->rx_dma_complete);

        init_completion(&tspi->xfer_completion);

        pm_runtime_enable(&pdev->dev);
        if (!pm_runtime_enabled(&pdev->dev)) {
                ret = tegra_spi_runtime_resume(&pdev->dev);
                if (ret)
                        goto exit_pm_disable;
        }

        ret = pm_runtime_get_sync(&pdev->dev);
        if (ret < 0) {
                dev_err(&pdev->dev, "pm runtime get failed, e = %d\n", ret);
                goto exit_pm_disable;
        }

        reset_control_assert(tspi->rst);
        udelay(2);
        reset_control_deassert(tspi->rst);
        tspi->def_command1_reg  = SPI_M_S;
        tegra_spi_writel(tspi, tspi->def_command1_reg, SPI_COMMAND1);
        pm_runtime_put(&pdev->dev);
        ret = request_threaded_irq(tspi->irq, tegra_spi_isr,
                                   tegra_spi_isr_thread, IRQF_ONESHOT,
                                   dev_name(&pdev->dev), tspi);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n",
                        tspi->irq);
                goto exit_pm_disable;
        }

        master->dev.of_node = pdev->dev.of_node;
        ret = devm_spi_register_master(&pdev->dev, master);
        if (ret < 0) {
                dev_err(&pdev->dev, "can not register to master err %d\n", ret);
                goto exit_free_irq;
        }
        return ret;

exit_free_irq:
        free_irq(spi_irq, tspi);
exit_pm_disable:
        pm_runtime_disable(&pdev->dev);
        if (!pm_runtime_status_suspended(&pdev->dev))
                tegra_spi_runtime_suspend(&pdev->dev);
        tegra_spi_deinit_dma_param(tspi, false);
exit_rx_dma_free:
        tegra_spi_deinit_dma_param(tspi, true);
exit_free_master:
        spi_master_put(master);
        return ret;
}

static int tegra_spi_remove(struct platform_device *pdev)
{
        struct spi_master *master = platform_get_drvdata(pdev);
        struct tegra_spi_data   *tspi = spi_master_get_devdata(master);

        free_irq(tspi->irq, tspi);

        if (tspi->tx_dma_chan)
                tegra_spi_deinit_dma_param(tspi, false);

        if (tspi->rx_dma_chan)
                tegra_spi_deinit_dma_param(tspi, true);

        pm_runtime_disable(&pdev->dev);
        if (!pm_runtime_status_suspended(&pdev->dev))
                tegra_spi_runtime_suspend(&pdev->dev);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int tegra_spi_suspend(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);

        return spi_master_suspend(master);
}

static int tegra_spi_resume(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct tegra_spi_data *tspi = spi_master_get_devdata(master);
        int ret;

        ret = pm_runtime_get_sync(dev);
        if (ret < 0) {
                dev_err(dev, "pm runtime failed, e = %d\n", ret);
                return ret;
        }
        tegra_spi_writel(tspi, tspi->command1_reg, SPI_COMMAND1);
        pm_runtime_put(dev);

        return spi_master_resume(master);
}
#endif

static int tegra_spi_runtime_suspend(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct tegra_spi_data *tspi = spi_master_get_devdata(master);

        /* Flush all write which are in PPSB queue by reading back */
        tegra_spi_readl(tspi, SPI_COMMAND1);

        clk_disable_unprepare(tspi->clk);
        return 0;
}

static int tegra_spi_runtime_resume(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct tegra_spi_data *tspi = spi_master_get_devdata(master);
        int ret;

        ret = clk_prepare_enable(tspi->clk);
        if (ret < 0) {
                dev_err(tspi->dev, "clk_prepare failed: %d\n", ret);
                return ret;
        }
        return 0;
}

static const struct dev_pm_ops tegra_spi_pm_ops = {
        SET_RUNTIME_PM_OPS(tegra_spi_runtime_suspend,
                tegra_spi_runtime_resume, NULL)
        SET_SYSTEM_SLEEP_PM_OPS(tegra_spi_suspend, tegra_spi_resume)
};
static struct platform_driver tegra_spi_driver = {
        .driver = {
                .name           = "spi-tegra114",
                .pm             = &tegra_spi_pm_ops,
                .of_match_table = tegra_spi_of_match,
        },
        .probe =        tegra_spi_probe,
        .remove =       tegra_spi_remove,
};
module_platform_driver(tegra_spi_driver);

MODULE_ALIAS("platform:spi-tegra114");
MODULE_DESCRIPTION("NVIDIA Tegra114 SPI Controller Driver");
MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_LICENSE("GPL v2");