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6840cc29 MF |
1 | /* |
2 | * Xtensa xtfpga SPI controller driver | |
3 | * | |
4 | * Copyright (c) 2014 Cadence Design Systems Inc. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | */ | |
10 | ||
11 | #include <linux/delay.h> | |
12 | #include <linux/io.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/of.h> | |
15 | #include <linux/platform_device.h> | |
16 | #include <linux/spi/spi.h> | |
17 | #include <linux/spi/spi_bitbang.h> | |
18 | ||
19 | #define XTFPGA_SPI_NAME "xtfpga_spi" | |
20 | ||
21 | #define XTFPGA_SPI_START 0x0 | |
22 | #define XTFPGA_SPI_BUSY 0x4 | |
23 | #define XTFPGA_SPI_DATA 0x8 | |
24 | ||
25 | #define BUSY_WAIT_US 100 | |
26 | ||
27 | struct xtfpga_spi { | |
28 | struct spi_bitbang bitbang; | |
29 | void __iomem *regs; | |
30 | u32 data; | |
31 | unsigned data_sz; | |
32 | }; | |
33 | ||
34 | static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi, | |
35 | unsigned addr, u32 val) | |
36 | { | |
37 | iowrite32(val, spi->regs + addr); | |
38 | } | |
39 | ||
40 | static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi, | |
41 | unsigned addr) | |
42 | { | |
43 | return ioread32(spi->regs + addr); | |
44 | } | |
45 | ||
46 | static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi) | |
47 | { | |
48 | unsigned i; | |
49 | for (i = 0; xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY) && | |
50 | i < BUSY_WAIT_US; ++i) | |
51 | udelay(1); | |
52 | WARN_ON_ONCE(i == BUSY_WAIT_US); | |
53 | } | |
54 | ||
55 | static u32 xtfpga_spi_txrx_word(struct spi_device *spi, unsigned nsecs, | |
56 | u32 v, u8 bits) | |
57 | { | |
58 | struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master); | |
59 | ||
60 | xspi->data = (xspi->data << bits) | (v & GENMASK(bits - 1, 0)); | |
61 | xspi->data_sz += bits; | |
62 | if (xspi->data_sz >= 16) { | |
63 | xtfpga_spi_write32(xspi, XTFPGA_SPI_DATA, | |
64 | xspi->data >> (xspi->data_sz - 16)); | |
65 | xspi->data_sz -= 16; | |
66 | xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 1); | |
67 | xtfpga_spi_wait_busy(xspi); | |
68 | xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0); | |
69 | } | |
70 | ||
71 | return 0; | |
72 | } | |
73 | ||
74 | static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on) | |
75 | { | |
76 | struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master); | |
77 | ||
78 | WARN_ON(xspi->data_sz != 0); | |
79 | xspi->data_sz = 0; | |
80 | } | |
81 | ||
82 | static int xtfpga_spi_probe(struct platform_device *pdev) | |
83 | { | |
84 | struct xtfpga_spi *xspi; | |
85 | struct resource *mem; | |
86 | int ret; | |
87 | struct spi_master *master; | |
88 | ||
89 | master = spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi)); | |
90 | if (!master) | |
91 | return -ENOMEM; | |
92 | ||
93 | master->flags = SPI_MASTER_NO_RX; | |
94 | master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16); | |
95 | master->bus_num = pdev->dev.id; | |
96 | master->dev.of_node = pdev->dev.of_node; | |
97 | ||
98 | xspi = spi_master_get_devdata(master); | |
99 | xspi->bitbang.master = master; | |
100 | xspi->bitbang.chipselect = xtfpga_spi_chipselect; | |
101 | xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word; | |
102 | ||
103 | mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
104 | if (!mem) { | |
105 | dev_err(&pdev->dev, "No memory resource\n"); | |
106 | ret = -ENODEV; | |
107 | goto err; | |
108 | } | |
109 | xspi->regs = devm_ioremap_resource(&pdev->dev, mem); | |
110 | if (IS_ERR(xspi->regs)) { | |
111 | ret = PTR_ERR(xspi->regs); | |
112 | goto err; | |
113 | } | |
114 | ||
115 | xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0); | |
116 | usleep_range(1000, 2000); | |
117 | if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) { | |
118 | dev_err(&pdev->dev, "Device stuck in busy state\n"); | |
119 | ret = -EBUSY; | |
120 | goto err; | |
121 | } | |
122 | ||
123 | ret = spi_bitbang_start(&xspi->bitbang); | |
124 | if (ret < 0) { | |
125 | dev_err(&pdev->dev, "spi_bitbang_start failed\n"); | |
126 | goto err; | |
127 | } | |
128 | ||
129 | platform_set_drvdata(pdev, master); | |
130 | return 0; | |
131 | err: | |
132 | spi_master_put(master); | |
133 | return ret; | |
134 | } | |
135 | ||
136 | static int xtfpga_spi_remove(struct platform_device *pdev) | |
137 | { | |
138 | struct spi_master *master = platform_get_drvdata(pdev); | |
139 | struct xtfpga_spi *xspi = spi_master_get_devdata(master); | |
140 | ||
141 | spi_bitbang_stop(&xspi->bitbang); | |
142 | spi_master_put(master); | |
143 | ||
144 | return 0; | |
145 | } | |
146 | ||
147 | MODULE_ALIAS("platform:" XTFPGA_SPI_NAME); | |
148 | ||
149 | #ifdef CONFIG_OF | |
150 | static const struct of_device_id xtfpga_spi_of_match[] = { | |
151 | { .compatible = "cdns,xtfpga-spi", }, | |
152 | {} | |
153 | }; | |
154 | MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match); | |
155 | #endif | |
156 | ||
157 | static struct platform_driver xtfpga_spi_driver = { | |
158 | .probe = xtfpga_spi_probe, | |
159 | .remove = xtfpga_spi_remove, | |
160 | .driver = { | |
161 | .name = XTFPGA_SPI_NAME, | |
162 | .owner = THIS_MODULE, | |
163 | .of_match_table = of_match_ptr(xtfpga_spi_of_match), | |
164 | }, | |
165 | }; | |
166 | module_platform_driver(xtfpga_spi_driver); | |
167 | ||
168 | MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>"); | |
169 | MODULE_DESCRIPTION("xtensa xtfpga SPI driver"); | |
170 | MODULE_LICENSE("GPL"); |