1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * OpenCores tiny SPI host 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
36struct 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
54static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
55{
56 return spi_controller_get_devdata(ctlr: sdev->controller);
57}
58
59static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)
60{
61 struct tiny_spi *hw = tiny_spi_to_hw(sdev: spi);
62
63 return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;
64}
65
66static int tiny_spi_setup_transfer(struct spi_device *spi,
67 struct spi_transfer *t)
68{
69 struct tiny_spi *hw = tiny_spi_to_hw(sdev: 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, hz: t->speed_hz);
75 }
76 writel(val: baud, addr: hw->base + TINY_SPI_BAUD);
77 writel(val: hw->mode, addr: hw->base + TINY_SPI_CONTROL);
78 return 0;
79}
80
81static int tiny_spi_setup(struct spi_device *spi)
82{
83 struct tiny_spi *hw = tiny_spi_to_hw(sdev: 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, hz: hw->speed_hz);
88 }
89 hw->mode = spi->mode & SPI_MODE_X_MASK;
90 return 0;
91}
92
93static inline void tiny_spi_wait_txr(struct tiny_spi *hw)
94{
95 while (!(readb(addr: hw->base + TINY_SPI_STATUS) &
96 TINY_SPI_STATUS_TXR))
97 cpu_relax();
98}
99
100static inline void tiny_spi_wait_txe(struct tiny_spi *hw)
101{
102 while (!(readb(addr: hw->base + TINY_SPI_STATUS) &
103 TINY_SPI_STATUS_TXE))
104 cpu_relax();
105}
106
107static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
108{
109 struct tiny_spi *hw = tiny_spi_to_hw(sdev: 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(val: hw->txp ? *hw->txp++ : 0,
125 addr: hw->base + TINY_SPI_TXDATA);
126 hw->txc++;
127 writeb(val: hw->txp ? *hw->txp++ : 0,
128 addr: hw->base + TINY_SPI_TXDATA);
129 hw->txc++;
130 writeb(TINY_SPI_STATUS_TXR, addr: hw->base + TINY_SPI_STATUS);
131 } else {
132 writeb(val: hw->txp ? *hw->txp++ : 0,
133 addr: hw->base + TINY_SPI_TXDATA);
134 hw->txc++;
135 writeb(TINY_SPI_STATUS_TXE, addr: 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(val: txp ? *txp++ : 0, addr: hw->base + TINY_SPI_TXDATA);
142 for (i = 1; i < t->len; i++) {
143 writeb(val: txp ? *txp++ : 0, addr: 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(addr: hw->base + TINY_SPI_TXDATA);
149 }
150 tiny_spi_wait_txe(hw);
151 if (rxp)
152 *rxp++ = readb(addr: hw->base + TINY_SPI_RXDATA);
153 }
154
155 return t->len;
156}
157
158static irqreturn_t tiny_spi_irq(int irq, void *dev)
159{
160 struct tiny_spi *hw = dev;
161
162 writeb(val: 0, addr: hw->base + TINY_SPI_STATUS);
163 if (hw->rxc + 1 == hw->len) {
164 if (hw->rxp)
165 *hw->rxp++ = readb(addr: hw->base + TINY_SPI_RXDATA);
166 hw->rxc++;
167 complete(&hw->done);
168 } else {
169 if (hw->rxp)
170 *hw->rxp++ = readb(addr: hw->base + TINY_SPI_TXDATA);
171 hw->rxc++;
172 if (hw->txc < hw->len) {
173 writeb(val: hw->txp ? *hw->txp++ : 0,
174 addr: hw->base + TINY_SPI_TXDATA);
175 hw->txc++;
176 writeb(TINY_SPI_STATUS_TXR,
177 addr: hw->base + TINY_SPI_STATUS);
178 } else {
179 writeb(TINY_SPI_STATUS_TXE,
180 addr: hw->base + TINY_SPI_STATUS);
181 }
182 }
183 return IRQ_HANDLED;
184}
185
186#ifdef CONFIG_OF
187static int tiny_spi_of_probe(struct platform_device *pdev)
188{
189 struct tiny_spi *hw = platform_get_drvdata(pdev);
190 struct device_node *np = pdev->dev.of_node;
191 u32 val;
192
193 if (!np)
194 return 0;
195 hw->bitbang.ctlr->dev.of_node = pdev->dev.of_node;
196 if (!of_property_read_u32(np, propname: "clock-frequency", out_value: &val))
197 hw->freq = val;
198 if (!of_property_read_u32(np, propname: "baud-width", out_value: &val))
199 hw->baudwidth = val;
200 return 0;
201}
202#else /* !CONFIG_OF */
203static int tiny_spi_of_probe(struct platform_device *pdev)
204{
205 return 0;
206}
207#endif /* CONFIG_OF */
208
209static int tiny_spi_probe(struct platform_device *pdev)
210{
211 struct tiny_spi_platform_data *platp = dev_get_platdata(dev: &pdev->dev);
212 struct tiny_spi *hw;
213 struct spi_controller *host;
214 int err = -ENODEV;
215
216 host = spi_alloc_host(dev: &pdev->dev, size: sizeof(struct tiny_spi));
217 if (!host)
218 return err;
219
220 /* setup the host state. */
221 host->bus_num = pdev->id;
222 host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
223 host->setup = tiny_spi_setup;
224 host->use_gpio_descriptors = true;
225
226 hw = spi_controller_get_devdata(ctlr: host);
227 platform_set_drvdata(pdev, data: hw);
228
229 /* setup the state for the bitbang driver */
230 hw->bitbang.ctlr = host;
231 hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
232 hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
233
234 /* find and map our resources */
235 hw->base = devm_platform_ioremap_resource(pdev, index: 0);
236 if (IS_ERR(ptr: hw->base)) {
237 err = PTR_ERR(ptr: hw->base);
238 goto exit;
239 }
240 /* irq is optional */
241 hw->irq = platform_get_irq(pdev, 0);
242 if (hw->irq >= 0) {
243 init_completion(x: &hw->done);
244 err = devm_request_irq(dev: &pdev->dev, irq: hw->irq, handler: tiny_spi_irq, irqflags: 0,
245 devname: pdev->name, dev_id: hw);
246 if (err)
247 goto exit;
248 }
249 /* find platform data */
250 if (platp) {
251 hw->freq = platp->freq;
252 hw->baudwidth = platp->baudwidth;
253 } else {
254 err = tiny_spi_of_probe(pdev);
255 if (err)
256 goto exit;
257 }
258
259 /* register our spi controller */
260 err = spi_bitbang_start(spi: &hw->bitbang);
261 if (err)
262 goto exit;
263 dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
264
265 return 0;
266
267exit:
268 spi_controller_put(ctlr: host);
269 return err;
270}
271
272static void tiny_spi_remove(struct platform_device *pdev)
273{
274 struct tiny_spi *hw = platform_get_drvdata(pdev);
275 struct spi_controller *host = hw->bitbang.ctlr;
276
277 spi_bitbang_stop(spi: &hw->bitbang);
278 spi_controller_put(ctlr: host);
279}
280
281#ifdef CONFIG_OF
282static const struct of_device_id tiny_spi_match[] = {
283 { .compatible = "opencores,tiny-spi-rtlsvn2", },
284 {},
285};
286MODULE_DEVICE_TABLE(of, tiny_spi_match);
287#endif /* CONFIG_OF */
288
289static struct platform_driver tiny_spi_driver = {
290 .probe = tiny_spi_probe,
291 .remove = tiny_spi_remove,
292 .driver = {
293 .name = DRV_NAME,
294 .pm = NULL,
295 .of_match_table = of_match_ptr(tiny_spi_match),
296 },
297};
298module_platform_driver(tiny_spi_driver);
299
300MODULE_DESCRIPTION("OpenCores tiny SPI driver");
301MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
302MODULE_LICENSE("GPL");
303MODULE_ALIAS("platform:" DRV_NAME);
304

source code of linux/drivers/spi/spi-oc-tiny.c