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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
ce792580 TC |
2 | /* |
3 | * OpenCores tiny SPI master driver | |
4 | * | |
3ea4eac3 | 5 | * https://opencores.org/project,tiny_spi |
ce792580 TC |
6 | * |
7 | * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw> | |
8 | * | |
9 | * Based on spi_s3c24xx.c, which is: | |
10 | * Copyright (c) 2006 Ben Dooks | |
11 | * Copyright (c) 2006 Simtec Electronics | |
12 | * Ben Dooks <ben@simtec.co.uk> | |
ce792580 TC |
13 | */ |
14 | ||
ce792580 TC |
15 | #include <linux/interrupt.h> |
16 | #include <linux/errno.h> | |
d7614de4 | 17 | #include <linux/module.h> |
ce792580 TC |
18 | #include <linux/platform_device.h> |
19 | #include <linux/spi/spi.h> | |
20 | #include <linux/spi/spi_bitbang.h> | |
21 | #include <linux/spi/spi_oc_tiny.h> | |
22 | #include <linux/io.h> | |
ce792580 TC |
23 | #include <linux/of.h> |
24 | ||
25 | #define DRV_NAME "spi_oc_tiny" | |
26 | ||
27 | #define TINY_SPI_RXDATA 0 | |
28 | #define TINY_SPI_TXDATA 4 | |
29 | #define TINY_SPI_STATUS 8 | |
30 | #define TINY_SPI_CONTROL 12 | |
31 | #define TINY_SPI_BAUD 16 | |
32 | ||
33 | #define TINY_SPI_STATUS_TXE 0x1 | |
34 | #define TINY_SPI_STATUS_TXR 0x2 | |
35 | ||
36 | struct tiny_spi { | |
37 | /* bitbang has to be first */ | |
38 | struct spi_bitbang bitbang; | |
39 | struct completion done; | |
40 | ||
41 | void __iomem *base; | |
42 | int irq; | |
43 | unsigned int freq; | |
44 | unsigned int baudwidth; | |
45 | unsigned int baud; | |
46 | unsigned int speed_hz; | |
47 | unsigned int mode; | |
48 | unsigned int len; | |
49 | unsigned int txc, rxc; | |
50 | const u8 *txp; | |
51 | u8 *rxp; | |
ce792580 TC |
52 | }; |
53 | ||
54 | static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev) | |
55 | { | |
56 | return spi_master_get_devdata(sdev->master); | |
57 | } | |
58 | ||
59 | static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz) | |
60 | { | |
61 | struct tiny_spi *hw = tiny_spi_to_hw(spi); | |
62 | ||
63 | return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1; | |
64 | } | |
65 | ||
ce792580 TC |
66 | static int tiny_spi_setup_transfer(struct spi_device *spi, |
67 | struct spi_transfer *t) | |
68 | { | |
69 | struct tiny_spi *hw = tiny_spi_to_hw(spi); | |
70 | unsigned int baud = hw->baud; | |
71 | ||
72 | if (t) { | |
73 | if (t->speed_hz && t->speed_hz != hw->speed_hz) | |
74 | baud = tiny_spi_baud(spi, t->speed_hz); | |
75 | } | |
76 | writel(baud, hw->base + TINY_SPI_BAUD); | |
77 | writel(hw->mode, hw->base + TINY_SPI_CONTROL); | |
78 | return 0; | |
79 | } | |
80 | ||
81 | static int tiny_spi_setup(struct spi_device *spi) | |
82 | { | |
83 | struct tiny_spi *hw = tiny_spi_to_hw(spi); | |
84 | ||
85 | if (spi->max_speed_hz != hw->speed_hz) { | |
86 | hw->speed_hz = spi->max_speed_hz; | |
87 | hw->baud = tiny_spi_baud(spi, hw->speed_hz); | |
88 | } | |
89 | hw->mode = spi->mode & (SPI_CPOL | SPI_CPHA); | |
90 | return 0; | |
91 | } | |
92 | ||
93 | static inline void tiny_spi_wait_txr(struct tiny_spi *hw) | |
94 | { | |
95 | while (!(readb(hw->base + TINY_SPI_STATUS) & | |
96 | TINY_SPI_STATUS_TXR)) | |
97 | cpu_relax(); | |
98 | } | |
99 | ||
100 | static inline void tiny_spi_wait_txe(struct tiny_spi *hw) | |
101 | { | |
102 | while (!(readb(hw->base + TINY_SPI_STATUS) & | |
103 | TINY_SPI_STATUS_TXE)) | |
104 | cpu_relax(); | |
105 | } | |
106 | ||
107 | static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t) | |
108 | { | |
109 | struct tiny_spi *hw = tiny_spi_to_hw(spi); | |
110 | const u8 *txp = t->tx_buf; | |
111 | u8 *rxp = t->rx_buf; | |
112 | unsigned int i; | |
113 | ||
114 | if (hw->irq >= 0) { | |
886db6ac | 115 | /* use interrupt driven data transfer */ |
ce792580 TC |
116 | hw->len = t->len; |
117 | hw->txp = t->tx_buf; | |
118 | hw->rxp = t->rx_buf; | |
119 | hw->txc = 0; | |
120 | hw->rxc = 0; | |
121 | ||
122 | /* send the first byte */ | |
123 | if (t->len > 1) { | |
124 | writeb(hw->txp ? *hw->txp++ : 0, | |
125 | hw->base + TINY_SPI_TXDATA); | |
126 | hw->txc++; | |
127 | writeb(hw->txp ? *hw->txp++ : 0, | |
128 | hw->base + TINY_SPI_TXDATA); | |
129 | hw->txc++; | |
130 | writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS); | |
131 | } else { | |
132 | writeb(hw->txp ? *hw->txp++ : 0, | |
133 | hw->base + TINY_SPI_TXDATA); | |
134 | hw->txc++; | |
135 | writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS); | |
136 | } | |
137 | ||
138 | wait_for_completion(&hw->done); | |
ce792580 | 139 | } else { |
e826a7ff AL |
140 | /* we need to tighten the transfer loop */ |
141 | writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA); | |
142 | for (i = 1; i < t->len; i++) { | |
143 | writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA); | |
144 | ||
145 | if (rxp || (i != t->len - 1)) | |
ce792580 | 146 | tiny_spi_wait_txr(hw); |
e826a7ff AL |
147 | if (rxp) |
148 | *rxp++ = readb(hw->base + TINY_SPI_TXDATA); | |
ce792580 TC |
149 | } |
150 | tiny_spi_wait_txe(hw); | |
e826a7ff AL |
151 | if (rxp) |
152 | *rxp++ = readb(hw->base + TINY_SPI_RXDATA); | |
ce792580 | 153 | } |
e826a7ff | 154 | |
ce792580 TC |
155 | return t->len; |
156 | } | |
157 | ||
158 | static irqreturn_t tiny_spi_irq(int irq, void *dev) | |
159 | { | |
160 | struct tiny_spi *hw = dev; | |
161 | ||
162 | writeb(0, hw->base + TINY_SPI_STATUS); | |
163 | if (hw->rxc + 1 == hw->len) { | |
164 | if (hw->rxp) | |
165 | *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA); | |
166 | hw->rxc++; | |
167 | complete(&hw->done); | |
168 | } else { | |
169 | if (hw->rxp) | |
170 | *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA); | |
171 | hw->rxc++; | |
172 | if (hw->txc < hw->len) { | |
173 | writeb(hw->txp ? *hw->txp++ : 0, | |
174 | hw->base + TINY_SPI_TXDATA); | |
175 | hw->txc++; | |
176 | writeb(TINY_SPI_STATUS_TXR, | |
177 | hw->base + TINY_SPI_STATUS); | |
178 | } else { | |
179 | writeb(TINY_SPI_STATUS_TXE, | |
180 | hw->base + TINY_SPI_STATUS); | |
181 | } | |
182 | } | |
183 | return IRQ_HANDLED; | |
184 | } | |
185 | ||
186 | #ifdef CONFIG_OF | |
187 | #include <linux/of_gpio.h> | |
188 | ||
fd4a319b | 189 | static int tiny_spi_of_probe(struct platform_device *pdev) |
ce792580 TC |
190 | { |
191 | struct tiny_spi *hw = platform_get_drvdata(pdev); | |
192 | struct device_node *np = pdev->dev.of_node; | |
45a3e771 | 193 | u32 val; |
ce792580 TC |
194 | |
195 | if (!np) | |
196 | return 0; | |
ce792580 | 197 | hw->bitbang.master->dev.of_node = pdev->dev.of_node; |
45a3e771 TK |
198 | if (!of_property_read_u32(np, "clock-frequency", &val)) |
199 | hw->freq = val; | |
200 | if (!of_property_read_u32(np, "baud-width", &val)) | |
201 | hw->baudwidth = val; | |
ce792580 TC |
202 | return 0; |
203 | } | |
204 | #else /* !CONFIG_OF */ | |
fd4a319b | 205 | static int tiny_spi_of_probe(struct platform_device *pdev) |
ce792580 TC |
206 | { |
207 | return 0; | |
208 | } | |
209 | #endif /* CONFIG_OF */ | |
210 | ||
fd4a319b | 211 | static int tiny_spi_probe(struct platform_device *pdev) |
ce792580 | 212 | { |
8074cf06 | 213 | struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev); |
ce792580 TC |
214 | struct tiny_spi *hw; |
215 | struct spi_master *master; | |
ce792580 TC |
216 | int err = -ENODEV; |
217 | ||
218 | master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi)); | |
219 | if (!master) | |
220 | return err; | |
221 | ||
222 | /* setup the master state. */ | |
223 | master->bus_num = pdev->id; | |
ce792580 TC |
224 | master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH; |
225 | master->setup = tiny_spi_setup; | |
f03ee204 | 226 | master->use_gpio_descriptors = true; |
ce792580 TC |
227 | |
228 | hw = spi_master_get_devdata(master); | |
229 | platform_set_drvdata(pdev, hw); | |
230 | ||
231 | /* setup the state for the bitbang driver */ | |
94c69f76 | 232 | hw->bitbang.master = master; |
ce792580 | 233 | hw->bitbang.setup_transfer = tiny_spi_setup_transfer; |
ce792580 TC |
234 | hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs; |
235 | ||
236 | /* find and map our resources */ | |
f601a654 | 237 | hw->base = devm_platform_ioremap_resource(pdev, 0); |
b3136f8f JL |
238 | if (IS_ERR(hw->base)) { |
239 | err = PTR_ERR(hw->base); | |
240 | goto exit; | |
241 | } | |
ce792580 TC |
242 | /* irq is optional */ |
243 | hw->irq = platform_get_irq(pdev, 0); | |
244 | if (hw->irq >= 0) { | |
245 | init_completion(&hw->done); | |
246 | err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0, | |
247 | pdev->name, hw); | |
248 | if (err) | |
249 | goto exit; | |
250 | } | |
251 | /* find platform data */ | |
252 | if (platp) { | |
ce792580 TC |
253 | hw->freq = platp->freq; |
254 | hw->baudwidth = platp->baudwidth; | |
255 | } else { | |
256 | err = tiny_spi_of_probe(pdev); | |
257 | if (err) | |
258 | goto exit; | |
259 | } | |
ce792580 TC |
260 | |
261 | /* register our spi controller */ | |
262 | err = spi_bitbang_start(&hw->bitbang); | |
263 | if (err) | |
264 | goto exit; | |
265 | dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq); | |
266 | ||
267 | return 0; | |
268 | ||
ce792580 | 269 | exit: |
ce792580 TC |
270 | spi_master_put(master); |
271 | return err; | |
272 | } | |
273 | ||
fd4a319b | 274 | static int tiny_spi_remove(struct platform_device *pdev) |
ce792580 TC |
275 | { |
276 | struct tiny_spi *hw = platform_get_drvdata(pdev); | |
277 | struct spi_master *master = hw->bitbang.master; | |
ce792580 TC |
278 | |
279 | spi_bitbang_stop(&hw->bitbang); | |
ce792580 TC |
280 | spi_master_put(master); |
281 | return 0; | |
282 | } | |
283 | ||
284 | #ifdef CONFIG_OF | |
285 | static const struct of_device_id tiny_spi_match[] = { | |
286 | { .compatible = "opencores,tiny-spi-rtlsvn2", }, | |
287 | {}, | |
288 | }; | |
289 | MODULE_DEVICE_TABLE(of, tiny_spi_match); | |
ce792580 TC |
290 | #endif /* CONFIG_OF */ |
291 | ||
292 | static struct platform_driver tiny_spi_driver = { | |
293 | .probe = tiny_spi_probe, | |
fd4a319b | 294 | .remove = tiny_spi_remove, |
ce792580 TC |
295 | .driver = { |
296 | .name = DRV_NAME, | |
ce792580 | 297 | .pm = NULL, |
9547acce | 298 | .of_match_table = of_match_ptr(tiny_spi_match), |
ce792580 TC |
299 | }, |
300 | }; | |
940ab889 | 301 | module_platform_driver(tiny_spi_driver); |
ce792580 TC |
302 | |
303 | MODULE_DESCRIPTION("OpenCores tiny SPI driver"); | |
304 | MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>"); | |
305 | MODULE_LICENSE("GPL"); | |
306 | MODULE_ALIAS("platform:" DRV_NAME); |