xref: /openbmc/u-boot/drivers/spi/pl022_spi.c (revision fb1b7712) 
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * (C) Copyright 2012
4  * Armando Visconti, ST Microelectronics, armando.visconti@st.com.
5  *
6  * (C) Copyright 2018
7  * Quentin Schulz, Bootlin, quentin.schulz@bootlin.com
8  *
9  * Driver for ARM PL022 SPI Controller.
10  */
11 
12 #include <clk.h>
13 #include <common.h>
14 #include <dm.h>
15 #include <dm/platform_data/spi_pl022.h>
16 #include <linux/io.h>
17 #include <spi.h>
18 
19 #define SSP_CR0		0x000
20 #define SSP_CR1		0x004
21 #define SSP_DR		0x008
22 #define SSP_SR		0x00C
23 #define SSP_CPSR	0x010
24 #define SSP_IMSC	0x014
25 #define SSP_RIS		0x018
26 #define SSP_MIS		0x01C
27 #define SSP_ICR		0x020
28 #define SSP_DMACR	0x024
29 #define SSP_CSR		0x030 /* vendor extension */
30 #define SSP_ITCR	0x080
31 #define SSP_ITIP	0x084
32 #define SSP_ITOP	0x088
33 #define SSP_TDR		0x08C
34 
35 #define SSP_PID0	0xFE0
36 #define SSP_PID1	0xFE4
37 #define SSP_PID2	0xFE8
38 #define SSP_PID3	0xFEC
39 
40 #define SSP_CID0	0xFF0
41 #define SSP_CID1	0xFF4
42 #define SSP_CID2	0xFF8
43 #define SSP_CID3	0xFFC
44 
45 /* SSP Control Register 0  - SSP_CR0 */
46 #define SSP_CR0_SPO		(0x1 << 6)
47 #define SSP_CR0_SPH		(0x1 << 7)
48 #define SSP_CR0_BIT_MODE(x)	((x) - 1)
49 #define SSP_SCR_MIN		(0x00)
50 #define SSP_SCR_MAX		(0xFF)
51 #define SSP_SCR_SHFT		8
52 #define DFLT_CLKRATE		2
53 
54 /* SSP Control Register 1  - SSP_CR1 */
55 #define SSP_CR1_MASK_SSE	(0x1 << 1)
56 
57 #define SSP_CPSR_MIN		(0x02)
58 #define SSP_CPSR_MAX		(0xFE)
59 #define DFLT_PRESCALE		(0x40)
60 
61 /* SSP Status Register - SSP_SR */
62 #define SSP_SR_MASK_TFE		(0x1 << 0) /* Transmit FIFO empty */
63 #define SSP_SR_MASK_TNF		(0x1 << 1) /* Transmit FIFO not full */
64 #define SSP_SR_MASK_RNE		(0x1 << 2) /* Receive FIFO not empty */
65 #define SSP_SR_MASK_RFF		(0x1 << 3) /* Receive FIFO full */
66 #define SSP_SR_MASK_BSY		(0x1 << 4) /* Busy Flag */
67 
68 struct pl022_spi_slave {
69 	void *base;
70 	unsigned int freq;
71 };
72 
73 /*
74  * ARM PL022 exists in different 'flavors'.
75  * This drivers currently support the standard variant (0x00041022), that has a
76  * 16bit wide and 8 locations deep TX/RX FIFO.
77  */
78 static int pl022_is_supported(struct pl022_spi_slave *ps)
79 {
80 	/* PL022 version is 0x00041022 */
81 	if ((readw(ps->base + SSP_PID0) == 0x22) &&
82 	    (readw(ps->base + SSP_PID1) == 0x10) &&
83 	    ((readw(ps->base + SSP_PID2) & 0xf) == 0x04) &&
84 	    (readw(ps->base + SSP_PID3) == 0x00))
85 		return 1;
86 
87 	return 0;
88 }
89 
90 static int pl022_spi_probe(struct udevice *bus)
91 {
92 	struct pl022_spi_pdata *plat = dev_get_platdata(bus);
93 	struct pl022_spi_slave *ps = dev_get_priv(bus);
94 
95 	ps->base = ioremap(plat->addr, plat->size);
96 	ps->freq = plat->freq;
97 
98 	/* Check the PL022 version */
99 	if (!pl022_is_supported(ps))
100 		return -ENOTSUPP;
101 
102 	/* 8 bits per word, high polarity and default clock rate */
103 	writew(SSP_CR0_BIT_MODE(8), ps->base + SSP_CR0);
104 	writew(DFLT_PRESCALE, ps->base + SSP_CPSR);
105 
106 	return 0;
107 }
108 
109 static void flush(struct pl022_spi_slave *ps)
110 {
111 	do {
112 		while (readw(ps->base + SSP_SR) & SSP_SR_MASK_RNE)
113 			readw(ps->base + SSP_DR);
114 	} while (readw(ps->base + SSP_SR) & SSP_SR_MASK_BSY);
115 }
116 
117 static int pl022_spi_claim_bus(struct udevice *dev)
118 {
119 	struct udevice *bus = dev->parent;
120 	struct pl022_spi_slave *ps = dev_get_priv(bus);
121 	u16 reg;
122 
123 	/* Enable the SPI hardware */
124 	reg = readw(ps->base + SSP_CR1);
125 	reg |= SSP_CR1_MASK_SSE;
126 	writew(reg, ps->base + SSP_CR1);
127 
128 	flush(ps);
129 
130 	return 0;
131 }
132 
133 static int pl022_spi_release_bus(struct udevice *dev)
134 {
135 	struct udevice *bus = dev->parent;
136 	struct pl022_spi_slave *ps = dev_get_priv(bus);
137 	u16 reg;
138 
139 	flush(ps);
140 
141 	/* Disable the SPI hardware */
142 	reg = readw(ps->base + SSP_CR1);
143 	reg &= ~SSP_CR1_MASK_SSE;
144 	writew(reg, ps->base + SSP_CR1);
145 
146 	return 0;
147 }
148 
149 static int pl022_spi_xfer(struct udevice *dev, unsigned int bitlen,
150 			  const void *dout, void *din, unsigned long flags)
151 {
152 	struct udevice *bus = dev->parent;
153 	struct pl022_spi_slave *ps = dev_get_priv(bus);
154 	u32		len_tx = 0, len_rx = 0, len;
155 	u32		ret = 0;
156 	const u8	*txp = dout;
157 	u8		*rxp = din, value;
158 
159 	if (bitlen == 0)
160 		/* Finish any previously submitted transfers */
161 		return 0;
162 
163 	/*
164 	 * TODO: The controller can do non-multiple-of-8 bit
165 	 * transfers, but this driver currently doesn't support it.
166 	 *
167 	 * It's also not clear how such transfers are supposed to be
168 	 * represented as a stream of bytes...this is a limitation of
169 	 * the current SPI interface.
170 	 */
171 	if (bitlen % 8) {
172 		/* Errors always terminate an ongoing transfer */
173 		flags |= SPI_XFER_END;
174 		return -1;
175 	}
176 
177 	len = bitlen / 8;
178 
179 	while (len_tx < len) {
180 		if (readw(ps->base + SSP_SR) & SSP_SR_MASK_TNF) {
181 			value = txp ? *txp++ : 0;
182 			writew(value, ps->base + SSP_DR);
183 			len_tx++;
184 		}
185 
186 		if (readw(ps->base + SSP_SR) & SSP_SR_MASK_RNE) {
187 			value = readw(ps->base + SSP_DR);
188 			if (rxp)
189 				*rxp++ = value;
190 			len_rx++;
191 		}
192 	}
193 
194 	while (len_rx < len_tx) {
195 		if (readw(ps->base + SSP_SR) & SSP_SR_MASK_RNE) {
196 			value = readw(ps->base + SSP_DR);
197 			if (rxp)
198 				*rxp++ = value;
199 			len_rx++;
200 		}
201 	}
202 
203 	return ret;
204 }
205 
206 static inline u32 spi_rate(u32 rate, u16 cpsdvsr, u16 scr)
207 {
208 	return rate / (cpsdvsr * (1 + scr));
209 }
210 
211 static int pl022_spi_set_speed(struct udevice *bus, uint speed)
212 {
213 	struct pl022_spi_slave *ps = dev_get_priv(bus);
214 	u16 scr = SSP_SCR_MIN, cr0 = 0, cpsr = SSP_CPSR_MIN, best_scr = scr,
215 	    best_cpsr = cpsr;
216 	u32 min, max, best_freq = 0, tmp;
217 	u32 rate = ps->freq;
218 	bool found = false;
219 
220 	max = spi_rate(rate, SSP_CPSR_MIN, SSP_SCR_MIN);
221 	min = spi_rate(rate, SSP_CPSR_MAX, SSP_SCR_MAX);
222 
223 	if (speed > max || speed < min) {
224 		pr_err("Tried to set speed to %dHz but min=%d and max=%d\n",
225 		       speed, min, max);
226 		return -EINVAL;
227 	}
228 
229 	while (cpsr <= SSP_CPSR_MAX && !found) {
230 		while (scr <= SSP_SCR_MAX) {
231 			tmp = spi_rate(rate, cpsr, scr);
232 
233 			if (abs(speed - tmp) < abs(speed - best_freq)) {
234 				best_freq = tmp;
235 				best_cpsr = cpsr;
236 				best_scr = scr;
237 
238 				if (tmp == speed) {
239 					found = true;
240 					break;
241 				}
242 			}
243 
244 			scr++;
245 		}
246 		cpsr += 2;
247 		scr = SSP_SCR_MIN;
248 	}
249 
250 	writew(best_cpsr, ps->base + SSP_CPSR);
251 	cr0 = readw(ps->base + SSP_CR0);
252 	writew(cr0 | (best_scr << SSP_SCR_SHFT), ps->base + SSP_CR0);
253 
254 	return 0;
255 }
256 
257 static int pl022_spi_set_mode(struct udevice *bus, uint mode)
258 {
259 	struct pl022_spi_slave *ps = dev_get_priv(bus);
260 	u16 reg;
261 
262 	reg = readw(ps->base + SSP_CR0);
263 	reg &= ~(SSP_CR0_SPH | SSP_CR0_SPO);
264 	if (mode & SPI_CPHA)
265 		reg |= SSP_CR0_SPH;
266 	if (mode & SPI_CPOL)
267 		reg |= SSP_CR0_SPO;
268 	writew(reg, ps->base + SSP_CR0);
269 
270 	return 0;
271 }
272 
273 static int pl022_cs_info(struct udevice *bus, uint cs,
274 			 struct spi_cs_info *info)
275 {
276 	return 0;
277 }
278 
279 static const struct dm_spi_ops pl022_spi_ops = {
280 	.claim_bus      = pl022_spi_claim_bus,
281 	.release_bus    = pl022_spi_release_bus,
282 	.xfer           = pl022_spi_xfer,
283 	.set_speed      = pl022_spi_set_speed,
284 	.set_mode       = pl022_spi_set_mode,
285 	.cs_info        = pl022_cs_info,
286 };
287 
288 #if !CONFIG_IS_ENABLED(OF_PLATDATA)
289 static int pl022_spi_ofdata_to_platdata(struct udevice *bus)
290 {
291 	struct pl022_spi_pdata *plat = bus->platdata;
292 	const void *fdt = gd->fdt_blob;
293 	int node = dev_of_offset(bus);
294 	struct clk clkdev;
295 	int ret;
296 
297 	plat->addr = fdtdec_get_addr_size(fdt, node, "reg", &plat->size);
298 
299 	ret = clk_get_by_index(bus, 0, &clkdev);
300 	if (ret)
301 		return ret;
302 
303 	plat->freq = clk_get_rate(&clkdev);
304 
305 	return 0;
306 }
307 
308 static const struct udevice_id pl022_spi_ids[] = {
309 	{ .compatible = "arm,pl022-spi" },
310 	{ }
311 };
312 #endif
313 
314 U_BOOT_DRIVER(pl022_spi) = {
315 	.name   = "pl022_spi",
316 	.id     = UCLASS_SPI,
317 #if !CONFIG_IS_ENABLED(OF_PLATDATA)
318 	.of_match = pl022_spi_ids,
319 	.ofdata_to_platdata = pl022_spi_ofdata_to_platdata,
320 #endif
321 	.ops    = &pl022_spi_ops,
322 	.platdata_auto_alloc_size = sizeof(struct pl022_spi_pdata),
323 	.priv_auto_alloc_size = sizeof(struct pl022_spi_slave),
324 	.probe  = pl022_spi_probe,
325 };
326