xref: /openbmc/u-boot/drivers/spi/designware_spi.c (revision 43730ba7) 
1 /*
2  * Designware master SPI core controller driver
3  *
4  * Copyright (C) 2014 Stefan Roese <sr@denx.de>
5  *
6  * Very loosely based on the Linux driver:
7  * drivers/spi/spi-dw.c, which is:
8  * Copyright (c) 2009, Intel Corporation.
9  *
10  * SPDX-License-Identifier:	GPL-2.0
11  */
12 
13 #include <common.h>
14 #include <dm.h>
15 #include <errno.h>
16 #include <malloc.h>
17 #include <spi.h>
18 #include <fdtdec.h>
19 #include <linux/compat.h>
20 #include <asm/io.h>
21 #include <asm/arch/clock_manager.h>
22 
23 DECLARE_GLOBAL_DATA_PTR;
24 
25 /* Register offsets */
26 #define DW_SPI_CTRL0			0x00
27 #define DW_SPI_CTRL1			0x04
28 #define DW_SPI_SSIENR			0x08
29 #define DW_SPI_MWCR			0x0c
30 #define DW_SPI_SER			0x10
31 #define DW_SPI_BAUDR			0x14
32 #define DW_SPI_TXFLTR			0x18
33 #define DW_SPI_RXFLTR			0x1c
34 #define DW_SPI_TXFLR			0x20
35 #define DW_SPI_RXFLR			0x24
36 #define DW_SPI_SR			0x28
37 #define DW_SPI_IMR			0x2c
38 #define DW_SPI_ISR			0x30
39 #define DW_SPI_RISR			0x34
40 #define DW_SPI_TXOICR			0x38
41 #define DW_SPI_RXOICR			0x3c
42 #define DW_SPI_RXUICR			0x40
43 #define DW_SPI_MSTICR			0x44
44 #define DW_SPI_ICR			0x48
45 #define DW_SPI_DMACR			0x4c
46 #define DW_SPI_DMATDLR			0x50
47 #define DW_SPI_DMARDLR			0x54
48 #define DW_SPI_IDR			0x58
49 #define DW_SPI_VERSION			0x5c
50 #define DW_SPI_DR			0x60
51 
52 /* Bit fields in CTRLR0 */
53 #define SPI_DFS_OFFSET			0
54 
55 #define SPI_FRF_OFFSET			4
56 #define SPI_FRF_SPI			0x0
57 #define SPI_FRF_SSP			0x1
58 #define SPI_FRF_MICROWIRE		0x2
59 #define SPI_FRF_RESV			0x3
60 
61 #define SPI_MODE_OFFSET			6
62 #define SPI_SCPH_OFFSET			6
63 #define SPI_SCOL_OFFSET			7
64 
65 #define SPI_TMOD_OFFSET			8
66 #define SPI_TMOD_MASK			(0x3 << SPI_TMOD_OFFSET)
67 #define	SPI_TMOD_TR			0x0		/* xmit & recv */
68 #define SPI_TMOD_TO			0x1		/* xmit only */
69 #define SPI_TMOD_RO			0x2		/* recv only */
70 #define SPI_TMOD_EPROMREAD		0x3		/* eeprom read mode */
71 
72 #define SPI_SLVOE_OFFSET		10
73 #define SPI_SRL_OFFSET			11
74 #define SPI_CFS_OFFSET			12
75 
76 /* Bit fields in SR, 7 bits */
77 #define SR_MASK				0x7f		/* cover 7 bits */
78 #define SR_BUSY				(1 << 0)
79 #define SR_TF_NOT_FULL			(1 << 1)
80 #define SR_TF_EMPT			(1 << 2)
81 #define SR_RF_NOT_EMPT			(1 << 3)
82 #define SR_RF_FULL			(1 << 4)
83 #define SR_TX_ERR			(1 << 5)
84 #define SR_DCOL				(1 << 6)
85 
86 #define RX_TIMEOUT			1000		/* timeout in ms */
87 
88 struct dw_spi_platdata {
89 	s32 frequency;		/* Default clock frequency, -1 for none */
90 	void __iomem *regs;
91 };
92 
93 struct dw_spi_priv {
94 	void __iomem *regs;
95 	unsigned int freq;		/* Default frequency */
96 	unsigned int mode;
97 
98 	int bits_per_word;
99 	u8 cs;			/* chip select pin */
100 	u8 tmode;		/* TR/TO/RO/EEPROM */
101 	u8 type;		/* SPI/SSP/MicroWire */
102 	int len;
103 
104 	u32 fifo_len;		/* depth of the FIFO buffer */
105 	void *tx;
106 	void *tx_end;
107 	void *rx;
108 	void *rx_end;
109 };
110 
111 static inline u32 dw_readl(struct dw_spi_priv *priv, u32 offset)
112 {
113 	return __raw_readl(priv->regs + offset);
114 }
115 
116 static inline void dw_writel(struct dw_spi_priv *priv, u32 offset, u32 val)
117 {
118 	__raw_writel(val, priv->regs + offset);
119 }
120 
121 static inline u16 dw_readw(struct dw_spi_priv *priv, u32 offset)
122 {
123 	return __raw_readw(priv->regs + offset);
124 }
125 
126 static inline void dw_writew(struct dw_spi_priv *priv, u32 offset, u16 val)
127 {
128 	__raw_writew(val, priv->regs + offset);
129 }
130 
131 static int dw_spi_ofdata_to_platdata(struct udevice *bus)
132 {
133 	struct dw_spi_platdata *plat = bus->platdata;
134 	const void *blob = gd->fdt_blob;
135 	int node = bus->of_offset;
136 
137 	plat->regs = (struct dw_spi *)fdtdec_get_addr(blob, node, "reg");
138 
139 	/* Use 500KHz as a suitable default */
140 	plat->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
141 					500000);
142 	debug("%s: regs=%p max-frequency=%d\n", __func__, plat->regs,
143 	      plat->frequency);
144 
145 	return 0;
146 }
147 
148 static inline void spi_enable_chip(struct dw_spi_priv *priv, int enable)
149 {
150 	dw_writel(priv, DW_SPI_SSIENR, (enable ? 1 : 0));
151 }
152 
153 /* Restart the controller, disable all interrupts, clean rx fifo */
154 static void spi_hw_init(struct dw_spi_priv *priv)
155 {
156 	spi_enable_chip(priv, 0);
157 	dw_writel(priv, DW_SPI_IMR, 0xff);
158 	spi_enable_chip(priv, 1);
159 
160 	/*
161 	 * Try to detect the FIFO depth if not set by interface driver,
162 	 * the depth could be from 2 to 256 from HW spec
163 	 */
164 	if (!priv->fifo_len) {
165 		u32 fifo;
166 
167 		for (fifo = 2; fifo <= 256; fifo++) {
168 			dw_writew(priv, DW_SPI_TXFLTR, fifo);
169 			if (fifo != dw_readw(priv, DW_SPI_TXFLTR))
170 				break;
171 		}
172 
173 		priv->fifo_len = (fifo == 2) ? 0 : fifo - 1;
174 		dw_writew(priv, DW_SPI_TXFLTR, 0);
175 	}
176 	debug("%s: fifo_len=%d\n", __func__, priv->fifo_len);
177 }
178 
179 static int dw_spi_probe(struct udevice *bus)
180 {
181 	struct dw_spi_platdata *plat = dev_get_platdata(bus);
182 	struct dw_spi_priv *priv = dev_get_priv(bus);
183 
184 	priv->regs = plat->regs;
185 	priv->freq = plat->frequency;
186 
187 	/* Currently only bits_per_word == 8 supported */
188 	priv->bits_per_word = 8;
189 
190 	priv->tmode = 0; /* Tx & Rx */
191 
192 	/* Basic HW init */
193 	spi_hw_init(priv);
194 
195 	return 0;
196 }
197 
198 /* Return the max entries we can fill into tx fifo */
199 static inline u32 tx_max(struct dw_spi_priv *priv)
200 {
201 	u32 tx_left, tx_room, rxtx_gap;
202 
203 	tx_left = (priv->tx_end - priv->tx) / (priv->bits_per_word >> 3);
204 	tx_room = priv->fifo_len - dw_readw(priv, DW_SPI_TXFLR);
205 
206 	/*
207 	 * Another concern is about the tx/rx mismatch, we
208 	 * thought about using (priv->fifo_len - rxflr - txflr) as
209 	 * one maximum value for tx, but it doesn't cover the
210 	 * data which is out of tx/rx fifo and inside the
211 	 * shift registers. So a control from sw point of
212 	 * view is taken.
213 	 */
214 	rxtx_gap = ((priv->rx_end - priv->rx) - (priv->tx_end - priv->tx)) /
215 		(priv->bits_per_word >> 3);
216 
217 	return min3(tx_left, tx_room, (u32)(priv->fifo_len - rxtx_gap));
218 }
219 
220 /* Return the max entries we should read out of rx fifo */
221 static inline u32 rx_max(struct dw_spi_priv *priv)
222 {
223 	u32 rx_left = (priv->rx_end - priv->rx) / (priv->bits_per_word >> 3);
224 
225 	return min_t(u32, rx_left, dw_readw(priv, DW_SPI_RXFLR));
226 }
227 
228 static void dw_writer(struct dw_spi_priv *priv)
229 {
230 	u32 max = tx_max(priv);
231 	u16 txw = 0;
232 
233 	while (max--) {
234 		/* Set the tx word if the transfer's original "tx" is not null */
235 		if (priv->tx_end - priv->len) {
236 			if (priv->bits_per_word == 8)
237 				txw = *(u8 *)(priv->tx);
238 			else
239 				txw = *(u16 *)(priv->tx);
240 		}
241 		dw_writew(priv, DW_SPI_DR, txw);
242 		debug("%s: tx=0x%02x\n", __func__, txw);
243 		priv->tx += priv->bits_per_word >> 3;
244 	}
245 }
246 
247 static int dw_reader(struct dw_spi_priv *priv)
248 {
249 	unsigned start = get_timer(0);
250 	u32 max;
251 	u16 rxw;
252 
253 	/* Wait for rx data to be ready */
254 	while (rx_max(priv) == 0) {
255 		if (get_timer(start) > RX_TIMEOUT)
256 			return -ETIMEDOUT;
257 	}
258 
259 	max = rx_max(priv);
260 
261 	while (max--) {
262 		rxw = dw_readw(priv, DW_SPI_DR);
263 		debug("%s: rx=0x%02x\n", __func__, rxw);
264 
265 		/*
266 		 * Care about rx only if the transfer's original "rx" is
267 		 * not null
268 		 */
269 		if (priv->rx_end - priv->len) {
270 			if (priv->bits_per_word == 8)
271 				*(u8 *)(priv->rx) = rxw;
272 			else
273 				*(u16 *)(priv->rx) = rxw;
274 		}
275 		priv->rx += priv->bits_per_word >> 3;
276 	}
277 
278 	return 0;
279 }
280 
281 static int poll_transfer(struct dw_spi_priv *priv)
282 {
283 	int ret;
284 
285 	do {
286 		dw_writer(priv);
287 		ret = dw_reader(priv);
288 		if (ret < 0)
289 			return ret;
290 	} while (priv->rx_end > priv->rx);
291 
292 	return 0;
293 }
294 
295 static int dw_spi_xfer(struct udevice *dev, unsigned int bitlen,
296 		       const void *dout, void *din, unsigned long flags)
297 {
298 	struct udevice *bus = dev->parent;
299 	struct dw_spi_priv *priv = dev_get_priv(bus);
300 	const u8 *tx = dout;
301 	u8 *rx = din;
302 	int ret = 0;
303 	u32 cr0 = 0;
304 	u32 cs;
305 
306 	/* spi core configured to do 8 bit transfers */
307 	if (bitlen % 8) {
308 		debug("Non byte aligned SPI transfer.\n");
309 		return -1;
310 	}
311 
312 	cr0 = (priv->bits_per_word - 1) | (priv->type << SPI_FRF_OFFSET) |
313 		(priv->mode << SPI_MODE_OFFSET) |
314 		(priv->tmode << SPI_TMOD_OFFSET);
315 
316 	if (rx && tx)
317 		priv->tmode = SPI_TMOD_TR;
318 	else if (rx)
319 		priv->tmode = SPI_TMOD_RO;
320 	else
321 		priv->tmode = SPI_TMOD_TO;
322 
323 	cr0 &= ~SPI_TMOD_MASK;
324 	cr0 |= (priv->tmode << SPI_TMOD_OFFSET);
325 
326 	priv->len = bitlen >> 3;
327 	debug("%s: rx=%p tx=%p len=%d [bytes]\n", __func__, rx, tx, priv->len);
328 
329 	priv->tx = (void *)tx;
330 	priv->tx_end = priv->tx + priv->len;
331 	priv->rx = rx;
332 	priv->rx_end = priv->rx + priv->len;
333 
334 	/* Disable controller before writing control registers */
335 	spi_enable_chip(priv, 0);
336 
337 	debug("%s: cr0=%08x\n", __func__, cr0);
338 	/* Reprogram cr0 only if changed */
339 	if (dw_readw(priv, DW_SPI_CTRL0) != cr0)
340 		dw_writew(priv, DW_SPI_CTRL0, cr0);
341 
342 	/*
343 	 * Configure the desired SS (slave select 0...3) in the controller
344 	 * The DW SPI controller will activate and deactivate this CS
345 	 * automatically. So no cs_activate() etc is needed in this driver.
346 	 */
347 	cs = spi_chip_select(dev);
348 	dw_writel(priv, DW_SPI_SER, 1 << cs);
349 
350 	/* Enable controller after writing control registers */
351 	spi_enable_chip(priv, 1);
352 
353 	/* Start transfer in a polling loop */
354 	ret = poll_transfer(priv);
355 
356 	return ret;
357 }
358 
359 static int dw_spi_set_speed(struct udevice *bus, uint speed)
360 {
361 	struct dw_spi_platdata *plat = bus->platdata;
362 	struct dw_spi_priv *priv = dev_get_priv(bus);
363 	u16 clk_div;
364 
365 	if (speed > plat->frequency)
366 		speed = plat->frequency;
367 
368 	/* Disable controller before writing control registers */
369 	spi_enable_chip(priv, 0);
370 
371 	/* clk_div doesn't support odd number */
372 	clk_div = cm_get_spi_controller_clk_hz() / speed;
373 	clk_div = (clk_div + 1) & 0xfffe;
374 	dw_writel(priv, DW_SPI_BAUDR, clk_div);
375 
376 	/* Enable controller after writing control registers */
377 	spi_enable_chip(priv, 1);
378 
379 	priv->freq = speed;
380 	debug("%s: regs=%p speed=%d clk_div=%d\n", __func__, priv->regs,
381 	      priv->freq, clk_div);
382 
383 	return 0;
384 }
385 
386 static int dw_spi_set_mode(struct udevice *bus, uint mode)
387 {
388 	struct dw_spi_priv *priv = dev_get_priv(bus);
389 
390 	/*
391 	 * Can't set mode yet. Since this depends on if rx, tx, or
392 	 * rx & tx is requested. So we have to defer this to the
393 	 * real transfer function.
394 	 */
395 	priv->mode = mode;
396 	debug("%s: regs=%p, mode=%d\n", __func__, priv->regs, priv->mode);
397 
398 	return 0;
399 }
400 
401 static const struct dm_spi_ops dw_spi_ops = {
402 	.xfer		= dw_spi_xfer,
403 	.set_speed	= dw_spi_set_speed,
404 	.set_mode	= dw_spi_set_mode,
405 	/*
406 	 * cs_info is not needed, since we require all chip selects to be
407 	 * in the device tree explicitly
408 	 */
409 };
410 
411 static const struct udevice_id dw_spi_ids[] = {
412 	{ .compatible = "snps,dw-apb-ssi" },
413 	{ }
414 };
415 
416 U_BOOT_DRIVER(dw_spi) = {
417 	.name = "dw_spi",
418 	.id = UCLASS_SPI,
419 	.of_match = dw_spi_ids,
420 	.ops = &dw_spi_ops,
421 	.ofdata_to_platdata = dw_spi_ofdata_to_platdata,
422 	.platdata_auto_alloc_size = sizeof(struct dw_spi_platdata),
423 	.priv_auto_alloc_size = sizeof(struct dw_spi_priv),
424 	.probe = dw_spi_probe,
425 };
426