Commit | Line | Data |
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f8043872 CB |
1 | /* |
2 | * Driver for Broadcom BCM2835 SPI Controllers | |
3 | * | |
4 | * Copyright (C) 2012 Chris Boot | |
5 | * Copyright (C) 2013 Stephen Warren | |
6 | * | |
7 | * This driver is inspired by: | |
8 | * spi-ath79.c, Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org> | |
9 | * spi-atmel.c, Copyright (C) 2006 Atmel Corporation | |
10 | * | |
11 | * This program is free software; you can redistribute it and/or modify | |
12 | * it under the terms of the GNU General Public License as published by | |
13 | * the Free Software Foundation; either version 2 of the License, or | |
14 | * (at your option) any later version. | |
15 | * | |
16 | * This program is distributed in the hope that it will be useful, | |
17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
19 | * GNU General Public License for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU General Public License | |
22 | * along with this program; if not, write to the Free Software | |
23 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
24 | */ | |
25 | ||
26 | #include <linux/clk.h> | |
27 | #include <linux/completion.h> | |
28 | #include <linux/delay.h> | |
29 | #include <linux/err.h> | |
30 | #include <linux/interrupt.h> | |
31 | #include <linux/io.h> | |
32 | #include <linux/kernel.h> | |
33 | #include <linux/module.h> | |
34 | #include <linux/of.h> | |
35 | #include <linux/of_irq.h> | |
36 | #include <linux/of_device.h> | |
37 | #include <linux/spi/spi.h> | |
38 | ||
39 | /* SPI register offsets */ | |
40 | #define BCM2835_SPI_CS 0x00 | |
41 | #define BCM2835_SPI_FIFO 0x04 | |
42 | #define BCM2835_SPI_CLK 0x08 | |
43 | #define BCM2835_SPI_DLEN 0x0c | |
44 | #define BCM2835_SPI_LTOH 0x10 | |
45 | #define BCM2835_SPI_DC 0x14 | |
46 | ||
47 | /* Bitfields in CS */ | |
48 | #define BCM2835_SPI_CS_LEN_LONG 0x02000000 | |
49 | #define BCM2835_SPI_CS_DMA_LEN 0x01000000 | |
50 | #define BCM2835_SPI_CS_CSPOL2 0x00800000 | |
51 | #define BCM2835_SPI_CS_CSPOL1 0x00400000 | |
52 | #define BCM2835_SPI_CS_CSPOL0 0x00200000 | |
53 | #define BCM2835_SPI_CS_RXF 0x00100000 | |
54 | #define BCM2835_SPI_CS_RXR 0x00080000 | |
55 | #define BCM2835_SPI_CS_TXD 0x00040000 | |
56 | #define BCM2835_SPI_CS_RXD 0x00020000 | |
57 | #define BCM2835_SPI_CS_DONE 0x00010000 | |
58 | #define BCM2835_SPI_CS_LEN 0x00002000 | |
59 | #define BCM2835_SPI_CS_REN 0x00001000 | |
60 | #define BCM2835_SPI_CS_ADCS 0x00000800 | |
61 | #define BCM2835_SPI_CS_INTR 0x00000400 | |
62 | #define BCM2835_SPI_CS_INTD 0x00000200 | |
63 | #define BCM2835_SPI_CS_DMAEN 0x00000100 | |
64 | #define BCM2835_SPI_CS_TA 0x00000080 | |
65 | #define BCM2835_SPI_CS_CSPOL 0x00000040 | |
66 | #define BCM2835_SPI_CS_CLEAR_RX 0x00000020 | |
67 | #define BCM2835_SPI_CS_CLEAR_TX 0x00000010 | |
68 | #define BCM2835_SPI_CS_CPOL 0x00000008 | |
69 | #define BCM2835_SPI_CS_CPHA 0x00000004 | |
70 | #define BCM2835_SPI_CS_CS_10 0x00000002 | |
71 | #define BCM2835_SPI_CS_CS_01 0x00000001 | |
72 | ||
73 | #define BCM2835_SPI_TIMEOUT_MS 30000 | |
74 | #define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_NO_CS) | |
75 | ||
76 | #define DRV_NAME "spi-bcm2835" | |
77 | ||
78 | struct bcm2835_spi { | |
79 | void __iomem *regs; | |
80 | struct clk *clk; | |
81 | int irq; | |
82 | struct completion done; | |
83 | const u8 *tx_buf; | |
84 | u8 *rx_buf; | |
85 | int len; | |
86 | }; | |
87 | ||
88 | static inline u32 bcm2835_rd(struct bcm2835_spi *bs, unsigned reg) | |
89 | { | |
90 | return readl(bs->regs + reg); | |
91 | } | |
92 | ||
93 | static inline void bcm2835_wr(struct bcm2835_spi *bs, unsigned reg, u32 val) | |
94 | { | |
95 | writel(val, bs->regs + reg); | |
96 | } | |
97 | ||
98 | static inline void bcm2835_rd_fifo(struct bcm2835_spi *bs, int len) | |
99 | { | |
100 | u8 byte; | |
101 | ||
102 | while (len--) { | |
103 | byte = bcm2835_rd(bs, BCM2835_SPI_FIFO); | |
104 | if (bs->rx_buf) | |
105 | *bs->rx_buf++ = byte; | |
106 | } | |
107 | } | |
108 | ||
109 | static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs, int len) | |
110 | { | |
111 | u8 byte; | |
112 | ||
113 | if (len > bs->len) | |
114 | len = bs->len; | |
115 | ||
116 | while (len--) { | |
117 | byte = bs->tx_buf ? *bs->tx_buf++ : 0; | |
118 | bcm2835_wr(bs, BCM2835_SPI_FIFO, byte); | |
119 | bs->len--; | |
120 | } | |
121 | } | |
122 | ||
123 | static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) | |
124 | { | |
125 | struct spi_master *master = dev_id; | |
126 | struct bcm2835_spi *bs = spi_master_get_devdata(master); | |
127 | u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); | |
128 | ||
129 | /* | |
130 | * RXR - RX needs Reading. This means 12 (or more) bytes have been | |
131 | * transmitted and hence 12 (or more) bytes have been received. | |
132 | * | |
133 | * The FIFO is 16-bytes deep. We check for this interrupt to keep the | |
134 | * FIFO full; we have a 4-byte-time buffer for IRQ latency. We check | |
135 | * this before DONE (TX empty) just in case we delayed processing this | |
136 | * interrupt for some reason. | |
137 | * | |
138 | * We only check for this case if we have more bytes to TX; at the end | |
139 | * of the transfer, we ignore this pipelining optimization, and let | |
140 | * bcm2835_spi_finish_transfer() drain the RX FIFO. | |
141 | */ | |
142 | if (bs->len && (cs & BCM2835_SPI_CS_RXR)) { | |
143 | /* Read 12 bytes of data */ | |
144 | bcm2835_rd_fifo(bs, 12); | |
145 | ||
146 | /* Write up to 12 bytes */ | |
147 | bcm2835_wr_fifo(bs, 12); | |
148 | ||
149 | /* | |
150 | * We must have written something to the TX FIFO due to the | |
151 | * bs->len check above, so cannot be DONE. Hence, return | |
152 | * early. Note that DONE could also be set if we serviced an | |
153 | * RXR interrupt really late. | |
154 | */ | |
155 | return IRQ_HANDLED; | |
156 | } | |
157 | ||
158 | /* | |
159 | * DONE - TX empty. This occurs when we first enable the transfer | |
160 | * since we do not pre-fill the TX FIFO. At any other time, given that | |
161 | * we refill the TX FIFO above based on RXR, and hence ignore DONE if | |
162 | * RXR is set, DONE really does mean end-of-transfer. | |
163 | */ | |
164 | if (cs & BCM2835_SPI_CS_DONE) { | |
165 | if (bs->len) { /* First interrupt in a transfer */ | |
166 | bcm2835_wr_fifo(bs, 16); | |
167 | } else { /* Transfer complete */ | |
168 | /* Disable SPI interrupts */ | |
169 | cs &= ~(BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD); | |
170 | bcm2835_wr(bs, BCM2835_SPI_CS, cs); | |
171 | ||
172 | /* | |
173 | * Wake up bcm2835_spi_transfer_one(), which will call | |
174 | * bcm2835_spi_finish_transfer(), to drain the RX FIFO. | |
175 | */ | |
176 | complete(&bs->done); | |
177 | } | |
178 | ||
179 | return IRQ_HANDLED; | |
180 | } | |
181 | ||
182 | return IRQ_NONE; | |
183 | } | |
184 | ||
f8043872 CB |
185 | static int bcm2835_spi_start_transfer(struct spi_device *spi, |
186 | struct spi_transfer *tfr) | |
187 | { | |
188 | struct bcm2835_spi *bs = spi_master_get_devdata(spi->master); | |
189 | unsigned long spi_hz, clk_hz, cdiv; | |
190 | u32 cs = BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA; | |
191 | ||
192 | spi_hz = tfr->speed_hz; | |
193 | clk_hz = clk_get_rate(bs->clk); | |
194 | ||
195 | if (spi_hz >= clk_hz / 2) { | |
196 | cdiv = 2; /* clk_hz/2 is the fastest we can go */ | |
197 | } else if (spi_hz) { | |
198 | /* CDIV must be a power of two */ | |
199 | cdiv = roundup_pow_of_two(DIV_ROUND_UP(clk_hz, spi_hz)); | |
200 | ||
201 | if (cdiv >= 65536) | |
202 | cdiv = 0; /* 0 is the slowest we can go */ | |
203 | } else | |
204 | cdiv = 0; /* 0 is the slowest we can go */ | |
205 | ||
206 | if (spi->mode & SPI_CPOL) | |
207 | cs |= BCM2835_SPI_CS_CPOL; | |
208 | if (spi->mode & SPI_CPHA) | |
209 | cs |= BCM2835_SPI_CS_CPHA; | |
210 | ||
211 | if (!(spi->mode & SPI_NO_CS)) { | |
212 | if (spi->mode & SPI_CS_HIGH) { | |
213 | cs |= BCM2835_SPI_CS_CSPOL; | |
214 | cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select; | |
215 | } | |
216 | ||
217 | cs |= spi->chip_select; | |
218 | } | |
219 | ||
16735d02 | 220 | reinit_completion(&bs->done); |
f8043872 CB |
221 | bs->tx_buf = tfr->tx_buf; |
222 | bs->rx_buf = tfr->rx_buf; | |
223 | bs->len = tfr->len; | |
224 | ||
225 | bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv); | |
226 | /* | |
227 | * Enable the HW block. This will immediately trigger a DONE (TX | |
228 | * empty) interrupt, upon which we will fill the TX FIFO with the | |
229 | * first TX bytes. Pre-filling the TX FIFO here to avoid the | |
230 | * interrupt doesn't work:-( | |
231 | */ | |
232 | bcm2835_wr(bs, BCM2835_SPI_CS, cs); | |
233 | ||
234 | return 0; | |
235 | } | |
236 | ||
237 | static int bcm2835_spi_finish_transfer(struct spi_device *spi, | |
238 | struct spi_transfer *tfr, bool cs_change) | |
239 | { | |
240 | struct bcm2835_spi *bs = spi_master_get_devdata(spi->master); | |
241 | u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); | |
242 | ||
243 | /* Drain RX FIFO */ | |
244 | while (cs & BCM2835_SPI_CS_RXD) { | |
245 | bcm2835_rd_fifo(bs, 1); | |
246 | cs = bcm2835_rd(bs, BCM2835_SPI_CS); | |
247 | } | |
248 | ||
249 | if (tfr->delay_usecs) | |
250 | udelay(tfr->delay_usecs); | |
251 | ||
252 | if (cs_change) | |
253 | /* Clear TA flag */ | |
254 | bcm2835_wr(bs, BCM2835_SPI_CS, cs & ~BCM2835_SPI_CS_TA); | |
255 | ||
256 | return 0; | |
257 | } | |
258 | ||
f8043872 CB |
259 | static int bcm2835_spi_transfer_one(struct spi_master *master, |
260 | struct spi_message *mesg) | |
261 | { | |
262 | struct bcm2835_spi *bs = spi_master_get_devdata(master); | |
263 | struct spi_transfer *tfr; | |
264 | struct spi_device *spi = mesg->spi; | |
265 | int err = 0; | |
266 | unsigned int timeout; | |
267 | bool cs_change; | |
268 | ||
269 | list_for_each_entry(tfr, &mesg->transfers, transfer_list) { | |
f8043872 CB |
270 | err = bcm2835_spi_start_transfer(spi, tfr); |
271 | if (err) | |
272 | goto out; | |
273 | ||
274 | timeout = wait_for_completion_timeout(&bs->done, | |
275 | msecs_to_jiffies(BCM2835_SPI_TIMEOUT_MS)); | |
276 | if (!timeout) { | |
277 | err = -ETIMEDOUT; | |
278 | goto out; | |
279 | } | |
280 | ||
281 | cs_change = tfr->cs_change || | |
282 | list_is_last(&tfr->transfer_list, &mesg->transfers); | |
283 | ||
284 | err = bcm2835_spi_finish_transfer(spi, tfr, cs_change); | |
285 | if (err) | |
286 | goto out; | |
287 | ||
288 | mesg->actual_length += (tfr->len - bs->len); | |
289 | } | |
290 | ||
291 | out: | |
292 | /* Clear FIFOs, and disable the HW block */ | |
293 | bcm2835_wr(bs, BCM2835_SPI_CS, | |
294 | BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX); | |
295 | mesg->status = err; | |
296 | spi_finalize_current_message(master); | |
297 | ||
298 | return 0; | |
299 | } | |
300 | ||
301 | static int bcm2835_spi_probe(struct platform_device *pdev) | |
302 | { | |
303 | struct spi_master *master; | |
304 | struct bcm2835_spi *bs; | |
305 | struct resource *res; | |
306 | int err; | |
307 | ||
308 | master = spi_alloc_master(&pdev->dev, sizeof(*bs)); | |
309 | if (!master) { | |
310 | dev_err(&pdev->dev, "spi_alloc_master() failed\n"); | |
311 | return -ENOMEM; | |
312 | } | |
313 | ||
314 | platform_set_drvdata(pdev, master); | |
315 | ||
316 | master->mode_bits = BCM2835_SPI_MODE_BITS; | |
c2b6a3a8 | 317 | master->bits_per_word_mask = SPI_BPW_MASK(8); |
f8043872 | 318 | master->num_chipselect = 3; |
f8043872 CB |
319 | master->transfer_one_message = bcm2835_spi_transfer_one; |
320 | master->dev.of_node = pdev->dev.of_node; | |
321 | ||
322 | bs = spi_master_get_devdata(master); | |
323 | ||
324 | init_completion(&bs->done); | |
325 | ||
326 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
2d6e75e8 LN |
327 | bs->regs = devm_ioremap_resource(&pdev->dev, res); |
328 | if (IS_ERR(bs->regs)) { | |
329 | err = PTR_ERR(bs->regs); | |
f8043872 CB |
330 | goto out_master_put; |
331 | } | |
332 | ||
333 | bs->clk = devm_clk_get(&pdev->dev, NULL); | |
334 | if (IS_ERR(bs->clk)) { | |
335 | err = PTR_ERR(bs->clk); | |
336 | dev_err(&pdev->dev, "could not get clk: %d\n", err); | |
337 | goto out_master_put; | |
338 | } | |
339 | ||
340 | bs->irq = irq_of_parse_and_map(pdev->dev.of_node, 0); | |
341 | if (bs->irq <= 0) { | |
342 | dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq); | |
343 | err = bs->irq ? bs->irq : -ENODEV; | |
344 | goto out_master_put; | |
345 | } | |
346 | ||
347 | clk_prepare_enable(bs->clk); | |
348 | ||
08bc0544 JH |
349 | err = devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_interrupt, 0, |
350 | dev_name(&pdev->dev), master); | |
f8043872 CB |
351 | if (err) { |
352 | dev_err(&pdev->dev, "could not request IRQ: %d\n", err); | |
353 | goto out_clk_disable; | |
354 | } | |
355 | ||
356 | /* initialise the hardware */ | |
357 | bcm2835_wr(bs, BCM2835_SPI_CS, | |
358 | BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX); | |
359 | ||
247263db | 360 | err = devm_spi_register_master(&pdev->dev, master); |
f8043872 CB |
361 | if (err) { |
362 | dev_err(&pdev->dev, "could not register SPI master: %d\n", err); | |
08bc0544 | 363 | goto out_clk_disable; |
f8043872 CB |
364 | } |
365 | ||
366 | return 0; | |
367 | ||
f8043872 CB |
368 | out_clk_disable: |
369 | clk_disable_unprepare(bs->clk); | |
370 | out_master_put: | |
371 | spi_master_put(master); | |
372 | return err; | |
373 | } | |
374 | ||
375 | static int bcm2835_spi_remove(struct platform_device *pdev) | |
376 | { | |
e0b35b89 | 377 | struct spi_master *master = platform_get_drvdata(pdev); |
f8043872 CB |
378 | struct bcm2835_spi *bs = spi_master_get_devdata(master); |
379 | ||
f8043872 CB |
380 | /* Clear FIFOs, and disable the HW block */ |
381 | bcm2835_wr(bs, BCM2835_SPI_CS, | |
382 | BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX); | |
383 | ||
384 | clk_disable_unprepare(bs->clk); | |
f8043872 CB |
385 | |
386 | return 0; | |
387 | } | |
388 | ||
389 | static const struct of_device_id bcm2835_spi_match[] = { | |
390 | { .compatible = "brcm,bcm2835-spi", }, | |
391 | {} | |
392 | }; | |
393 | MODULE_DEVICE_TABLE(of, bcm2835_spi_match); | |
394 | ||
395 | static struct platform_driver bcm2835_spi_driver = { | |
396 | .driver = { | |
397 | .name = DRV_NAME, | |
398 | .owner = THIS_MODULE, | |
399 | .of_match_table = bcm2835_spi_match, | |
400 | }, | |
401 | .probe = bcm2835_spi_probe, | |
402 | .remove = bcm2835_spi_remove, | |
403 | }; | |
404 | module_platform_driver(bcm2835_spi_driver); | |
405 | ||
406 | MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835"); | |
407 | MODULE_AUTHOR("Chris Boot <bootc@bootc.net>"); | |
408 | MODULE_LICENSE("GPL v2"); |