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1/*
2 * SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs
3 *
4 * Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
5 *
6 * This driver has been based on the spi-gpio.c:
7 * Copyright (C) 2006,2008 David Brownell
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 *
13 */
14
15#include <linux/kernel.h>
807cc4b1 16#include <linux/module.h>
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17#include <linux/delay.h>
18#include <linux/spinlock.h>
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19#include <linux/platform_device.h>
20#include <linux/io.h>
21#include <linux/spi/spi.h>
22#include <linux/spi/spi_bitbang.h>
23#include <linux/bitops.h>
24#include <linux/gpio.h>
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25#include <linux/clk.h>
26#include <linux/err.h>
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27
28#include <asm/mach-ath79/ar71xx_regs.h>
29#include <asm/mach-ath79/ath79_spi_platform.h>
30
31#define DRV_NAME "ath79-spi"
32
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33#define ATH79_SPI_RRW_DELAY_FACTOR 12000
34#define MHZ (1000 * 1000)
35
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36struct ath79_spi {
37 struct spi_bitbang bitbang;
38 u32 ioc_base;
39 u32 reg_ctrl;
40 void __iomem *base;
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41 struct clk *clk;
42 unsigned rrw_delay;
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43};
44
45static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned reg)
46{
47 return ioread32(sp->base + reg);
48}
49
50static inline void ath79_spi_wr(struct ath79_spi *sp, unsigned reg, u32 val)
51{
52 iowrite32(val, sp->base + reg);
53}
54
55static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi)
56{
57 return spi_master_get_devdata(spi->master);
58}
59
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60static inline void ath79_spi_delay(struct ath79_spi *sp, unsigned nsecs)
61{
62 if (nsecs > sp->rrw_delay)
63 ndelay(nsecs - sp->rrw_delay);
64}
65
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66static void ath79_spi_chipselect(struct spi_device *spi, int is_active)
67{
68 struct ath79_spi *sp = ath79_spidev_to_sp(spi);
69 int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active;
70
71 if (is_active) {
72 /* set initial clock polarity */
73 if (spi->mode & SPI_CPOL)
74 sp->ioc_base |= AR71XX_SPI_IOC_CLK;
75 else
76 sp->ioc_base &= ~AR71XX_SPI_IOC_CLK;
77
78 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
79 }
80
22c76326 81 if (gpio_is_valid(spi->cs_gpio)) {
8efaef4d 82 /* SPI is normally active-low */
91829a9a 83 gpio_set_value_cansleep(spi->cs_gpio, cs_high);
8efaef4d 84 } else {
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85 u32 cs_bit = AR71XX_SPI_IOC_CS(spi->chip_select);
86
8efaef4d 87 if (cs_high)
22c76326 88 sp->ioc_base |= cs_bit;
8efaef4d 89 else
22c76326 90 sp->ioc_base &= ~cs_bit;
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91
92 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
93 }
94
95}
96
c4a31f43 97static void ath79_spi_enable(struct ath79_spi *sp)
8efaef4d 98{
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99 /* enable GPIO mode */
100 ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
101
102 /* save CTRL register */
103 sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL);
104 sp->ioc_base = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC);
105
106 /* TODO: setup speed? */
107 ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43);
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108}
109
110static void ath79_spi_disable(struct ath79_spi *sp)
111{
112 /* restore CTRL register */
113 ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl);
114 /* disable GPIO mode */
115 ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
116}
117
118static int ath79_spi_setup_cs(struct spi_device *spi)
119{
83f0f398 120 struct ath79_spi *sp = ath79_spidev_to_sp(spi);
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121 int status;
122
95d79419 123 status = 0;
22c76326 124 if (gpio_is_valid(spi->cs_gpio)) {
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125 unsigned long flags;
126
127 flags = GPIOF_DIR_OUT;
128 if (spi->mode & SPI_CS_HIGH)
95d79419 129 flags |= GPIOF_INIT_LOW;
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130 else
131 flags |= GPIOF_INIT_HIGH;
95d79419 132
85f62476 133 status = gpio_request_one(spi->cs_gpio, flags,
95d79419 134 dev_name(&spi->dev));
83f0f398 135 } else {
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136 u32 cs_bit = AR71XX_SPI_IOC_CS(spi->chip_select);
137
83f0f398 138 if (spi->mode & SPI_CS_HIGH)
22c76326 139 sp->ioc_base &= ~cs_bit;
83f0f398 140 else
22c76326 141 sp->ioc_base |= cs_bit;
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142
143 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
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144 }
145
95d79419 146 return status;
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147}
148
149static void ath79_spi_cleanup_cs(struct spi_device *spi)
150{
22c76326 151 if (gpio_is_valid(spi->cs_gpio)) {
85f62476 152 gpio_free(spi->cs_gpio);
8efaef4d 153 }
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154}
155
156static int ath79_spi_setup(struct spi_device *spi)
157{
158 int status = 0;
159
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160 if (!spi->controller_state) {
161 status = ath79_spi_setup_cs(spi);
162 if (status)
163 return status;
164 }
165
166 status = spi_bitbang_setup(spi);
167 if (status && !spi->controller_state)
168 ath79_spi_cleanup_cs(spi);
169
170 return status;
171}
172
173static void ath79_spi_cleanup(struct spi_device *spi)
174{
175 ath79_spi_cleanup_cs(spi);
176 spi_bitbang_cleanup(spi);
177}
178
179static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
180 u32 word, u8 bits)
181{
182 struct ath79_spi *sp = ath79_spidev_to_sp(spi);
183 u32 ioc = sp->ioc_base;
184
185 /* clock starts at inactive polarity */
186 for (word <<= (32 - bits); likely(bits); bits--) {
187 u32 out;
188
189 if (word & (1 << 31))
190 out = ioc | AR71XX_SPI_IOC_DO;
191 else
192 out = ioc & ~AR71XX_SPI_IOC_DO;
193
194 /* setup MSB (to slave) on trailing edge */
195 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
440114fd 196 ath79_spi_delay(sp, nsecs);
8efaef4d 197 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
440114fd 198 ath79_spi_delay(sp, nsecs);
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199 if (bits == 1)
200 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
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201
202 word <<= 1;
203 }
204
205 return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS);
206}
207
fd4a319b 208static int ath79_spi_probe(struct platform_device *pdev)
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209{
210 struct spi_master *master;
211 struct ath79_spi *sp;
212 struct ath79_spi_platform_data *pdata;
213 struct resource *r;
440114fd 214 unsigned long rate;
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215 int ret;
216
217 master = spi_alloc_master(&pdev->dev, sizeof(*sp));
218 if (master == NULL) {
219 dev_err(&pdev->dev, "failed to allocate spi master\n");
220 return -ENOMEM;
221 }
222
223 sp = spi_master_get_devdata(master);
85f62476 224 master->dev.of_node = pdev->dev.of_node;
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225 platform_set_drvdata(pdev, sp);
226
8074cf06 227 pdata = dev_get_platdata(&pdev->dev);
8efaef4d 228
24778be2 229 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
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230 master->setup = ath79_spi_setup;
231 master->cleanup = ath79_spi_cleanup;
232 if (pdata) {
233 master->bus_num = pdata->bus_num;
234 master->num_chipselect = pdata->num_chipselect;
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235 }
236
94c69f76 237 sp->bitbang.master = master;
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238 sp->bitbang.chipselect = ath79_spi_chipselect;
239 sp->bitbang.txrx_word[SPI_MODE_0] = ath79_spi_txrx_mode0;
240 sp->bitbang.setup_transfer = spi_bitbang_setup_transfer;
241 sp->bitbang.flags = SPI_CS_HIGH;
242
243 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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244 sp->base = devm_ioremap_resource(&pdev->dev, r);
245 if (IS_ERR(sp->base)) {
246 ret = PTR_ERR(sp->base);
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247 goto err_put_master;
248 }
249
a6f4c8e0 250 sp->clk = devm_clk_get(&pdev->dev, "ahb");
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251 if (IS_ERR(sp->clk)) {
252 ret = PTR_ERR(sp->clk);
a6f4c8e0 253 goto err_put_master;
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254 }
255
3e19acdc 256 ret = clk_prepare_enable(sp->clk);
440114fd 257 if (ret)
a6f4c8e0 258 goto err_put_master;
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259
260 rate = DIV_ROUND_UP(clk_get_rate(sp->clk), MHZ);
261 if (!rate) {
262 ret = -EINVAL;
263 goto err_clk_disable;
264 }
265
266 sp->rrw_delay = ATH79_SPI_RRW_DELAY_FACTOR / rate;
267 dev_dbg(&pdev->dev, "register read/write delay is %u nsecs\n",
268 sp->rrw_delay);
269
c4a31f43 270 ath79_spi_enable(sp);
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271 ret = spi_bitbang_start(&sp->bitbang);
272 if (ret)
c4a31f43 273 goto err_disable;
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274
275 return 0;
276
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277err_disable:
278 ath79_spi_disable(sp);
440114fd 279err_clk_disable:
3e19acdc 280 clk_disable_unprepare(sp->clk);
8efaef4d 281err_put_master:
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282 spi_master_put(sp->bitbang.master);
283
284 return ret;
285}
286
fd4a319b 287static int ath79_spi_remove(struct platform_device *pdev)
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288{
289 struct ath79_spi *sp = platform_get_drvdata(pdev);
290
291 spi_bitbang_stop(&sp->bitbang);
c4a31f43 292 ath79_spi_disable(sp);
3e19acdc 293 clk_disable_unprepare(sp->clk);
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294 spi_master_put(sp->bitbang.master);
295
296 return 0;
297}
298
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299static void ath79_spi_shutdown(struct platform_device *pdev)
300{
301 ath79_spi_remove(pdev);
302}
303
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304static const struct of_device_id ath79_spi_of_match[] = {
305 { .compatible = "qca,ar7100-spi", },
306 { },
307};
d7a32394 308MODULE_DEVICE_TABLE(of, ath79_spi_of_match);
85f62476 309
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310static struct platform_driver ath79_spi_driver = {
311 .probe = ath79_spi_probe,
fd4a319b 312 .remove = ath79_spi_remove,
7410e848 313 .shutdown = ath79_spi_shutdown,
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314 .driver = {
315 .name = DRV_NAME,
85f62476 316 .of_match_table = ath79_spi_of_match,
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317 },
318};
940ab889 319module_platform_driver(ath79_spi_driver);
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320
321MODULE_DESCRIPTION("SPI controller driver for Atheros AR71XX/AR724X/AR913X");
322MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
323MODULE_LICENSE("GPL v2");
324MODULE_ALIAS("platform:" DRV_NAME);