1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * OpenCores tiny SPI master driver
4 *
5 * https://opencores.org/project,tiny_spi
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>
13 */
14
15 #include <linux/interrupt.h>
16 #include <linux/errno.h>
17 #include <linux/module.h>
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>
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;
52 };
53
tiny_spi_to_hw(struct spi_device * sdev)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
tiny_spi_baud(struct spi_device * spi,unsigned int hz)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
tiny_spi_setup_transfer(struct spi_device * spi,struct spi_transfer * t)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
tiny_spi_setup(struct spi_device * spi)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
tiny_spi_wait_txr(struct tiny_spi * hw)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
tiny_spi_wait_txe(struct tiny_spi * hw)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
tiny_spi_txrx_bufs(struct spi_device * spi,struct spi_transfer * t)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) {
115 /* use interrupt driven data transfer */
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);
139 } else {
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))
146 tiny_spi_wait_txr(hw);
147 if (rxp)
148 *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
149 }
150 tiny_spi_wait_txe(hw);
151 if (rxp)
152 *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
153 }
154
155 return t->len;
156 }
157
tiny_spi_irq(int irq,void * dev)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
tiny_spi_of_probe(struct platform_device * pdev)189 static int tiny_spi_of_probe(struct platform_device *pdev)
190 {
191 struct tiny_spi *hw = platform_get_drvdata(pdev);
192 struct device_node *np = pdev->dev.of_node;
193 u32 val;
194
195 if (!np)
196 return 0;
197 hw->bitbang.master->dev.of_node = pdev->dev.of_node;
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;
202 return 0;
203 }
204 #else /* !CONFIG_OF */
tiny_spi_of_probe(struct platform_device * pdev)205 static int tiny_spi_of_probe(struct platform_device *pdev)
206 {
207 return 0;
208 }
209 #endif /* CONFIG_OF */
210
tiny_spi_probe(struct platform_device * pdev)211 static int tiny_spi_probe(struct platform_device *pdev)
212 {
213 struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
214 struct tiny_spi *hw;
215 struct spi_master *master;
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;
224 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
225 master->setup = tiny_spi_setup;
226 master->use_gpio_descriptors = true;
227
228 hw = spi_master_get_devdata(master);
229 platform_set_drvdata(pdev, hw);
230
231 /* setup the state for the bitbang driver */
232 hw->bitbang.master = master;
233 hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
234 hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
235
236 /* find and map our resources */
237 hw->base = devm_platform_ioremap_resource(pdev, 0);
238 if (IS_ERR(hw->base)) {
239 err = PTR_ERR(hw->base);
240 goto exit;
241 }
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) {
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 }
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
269 exit:
270 spi_master_put(master);
271 return err;
272 }
273
tiny_spi_remove(struct platform_device * pdev)274 static int tiny_spi_remove(struct platform_device *pdev)
275 {
276 struct tiny_spi *hw = platform_get_drvdata(pdev);
277 struct spi_master *master = hw->bitbang.master;
278
279 spi_bitbang_stop(&hw->bitbang);
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);
290 #endif /* CONFIG_OF */
291
292 static struct platform_driver tiny_spi_driver = {
293 .probe = tiny_spi_probe,
294 .remove = tiny_spi_remove,
295 .driver = {
296 .name = DRV_NAME,
297 .pm = NULL,
298 .of_match_table = of_match_ptr(tiny_spi_match),
299 },
300 };
301 module_platform_driver(tiny_spi_driver);
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);
307