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 */
pl022_is_supported(struct pl022_spi_slave * ps)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
pl022_spi_probe(struct udevice * bus)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
flush(struct pl022_spi_slave * ps)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
pl022_spi_claim_bus(struct udevice * dev)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
pl022_spi_release_bus(struct udevice * dev)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
pl022_spi_xfer(struct udevice * dev,unsigned int bitlen,const void * dout,void * din,unsigned long flags)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
spi_rate(u32 rate,u16 cpsdvsr,u16 scr)206 static inline u32 spi_rate(u32 rate, u16 cpsdvsr, u16 scr)
207 {
208 return rate / (cpsdvsr * (1 + scr));
209 }
210
pl022_spi_set_speed(struct udevice * bus,uint speed)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
pl022_spi_set_mode(struct udevice * bus,uint mode)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
pl022_cs_info(struct udevice * bus,uint cs,struct spi_cs_info * info)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)
pl022_spi_ofdata_to_platdata(struct udevice * bus)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