1 /*
2  * Copyright (C) 2015 Marvell International Ltd.
3  *
4  * Copyright (C) 2016 Stefan Roese <sr@denx.de>
5  *
6  * SPDX-License-Identifier:	GPL-2.0+
7  */
8 
9 #include <common.h>
10 #include <dm.h>
11 #include <malloc.h>
12 #include <spi.h>
13 #include <wait_bit.h>
14 #include <asm/io.h>
15 
16 DECLARE_GLOBAL_DATA_PTR;
17 
18 #define MVEBU_SPI_A3700_XFER_RDY		BIT(1)
19 #define MVEBU_SPI_A3700_FIFO_FLUSH		BIT(9)
20 #define MVEBU_SPI_A3700_BYTE_LEN		BIT(5)
21 #define MVEBU_SPI_A3700_CLK_PHA			BIT(6)
22 #define MVEBU_SPI_A3700_CLK_POL			BIT(7)
23 #define MVEBU_SPI_A3700_FIFO_EN			BIT(17)
24 #define MVEBU_SPI_A3700_SPI_EN_0		BIT(16)
25 #define MVEBU_SPI_A3700_CLK_PRESCALE_BIT	0
26 #define MVEBU_SPI_A3700_CLK_PRESCALE_MASK	\
27 	(0x1f << MVEBU_SPI_A3700_CLK_PRESCALE_BIT)
28 
29 /* SPI registers */
30 struct spi_reg {
31 	u32 ctrl;	/* 0x10600 */
32 	u32 cfg;	/* 0x10604 */
33 	u32 dout;	/* 0x10608 */
34 	u32 din;	/* 0x1060c */
35 };
36 
37 struct mvebu_spi_platdata {
38 	struct spi_reg *spireg;
39 	unsigned int frequency;
40 	unsigned int clock;
41 };
42 
43 static void spi_cs_activate(struct spi_reg *reg, int cs)
44 {
45 	setbits_le32(&reg->ctrl, MVEBU_SPI_A3700_SPI_EN_0 << cs);
46 }
47 
48 static void spi_cs_deactivate(struct spi_reg *reg, int cs)
49 {
50 	clrbits_le32(&reg->ctrl, MVEBU_SPI_A3700_SPI_EN_0 << cs);
51 }
52 
53 /**
54  * spi_legacy_shift_byte() - triggers the real SPI transfer
55  * @bytelen:	Indicate how many bytes to transfer.
56  * @dout:	Buffer address of what to send.
57  * @din:	Buffer address of where to receive.
58  *
59  * This function triggers the real SPI transfer in legacy mode. It
60  * will shift out char buffer from @dout, and shift in char buffer to
61  * @din, if necessary.
62  *
63  * This function assumes that only one byte is shifted at one time.
64  * However, it is not its responisbility to set the transfer type to
65  * one-byte. Also, it does not guarantee that it will work if transfer
66  * type becomes two-byte. See spi_set_legacy() for details.
67  *
68  * In legacy mode, simply write to the SPI_DOUT register will trigger
69  * the transfer.
70  *
71  * If @dout == NULL, which means no actual data needs to be sent out,
72  * then the function will shift out 0x00 in order to shift in data.
73  * The XFER_RDY flag is checked every time before accessing SPI_DOUT
74  * and SPI_DIN register.
75  *
76  * The number of transfers to be triggerred is decided by @bytelen.
77  *
78  * Return:	0 - cool
79  *		-ETIMEDOUT - XFER_RDY flag timeout
80  */
81 static int spi_legacy_shift_byte(struct spi_reg *reg, unsigned int bytelen,
82 				 const void *dout, void *din)
83 {
84 	const u8 *dout_8;
85 	u8 *din_8;
86 	int ret;
87 
88 	/* Use 0x00 as dummy dout */
89 	const u8 dummy_dout = 0x0;
90 	u32 pending_dout = 0x0;
91 
92 	/* dout_8: pointer of current dout */
93 	dout_8 = dout;
94 	/* din_8: pointer of current din */
95 	din_8 = din;
96 
97 	while (bytelen) {
98 		ret = wait_for_bit(__func__, &reg->ctrl,
99 				   MVEBU_SPI_A3700_XFER_RDY, true, 100, false);
100 		if (ret)
101 			return ret;
102 
103 		if (dout)
104 			pending_dout = (u32)*dout_8;
105 		else
106 			pending_dout = (u32)dummy_dout;
107 
108 		/* Trigger the xfer */
109 		writel(pending_dout, &reg->dout);
110 
111 		if (din) {
112 			ret = wait_for_bit(__func__, &reg->ctrl,
113 					   MVEBU_SPI_A3700_XFER_RDY,
114 					   true, 100, false);
115 			if (ret)
116 				return ret;
117 
118 			/* Read what is transferred in */
119 			*din_8 = (u8)readl(&reg->din);
120 		}
121 
122 		/* Don't increment the current pointer if NULL */
123 		if (dout)
124 			dout_8++;
125 		if (din)
126 			din_8++;
127 
128 		bytelen--;
129 	}
130 
131 	return 0;
132 }
133 
134 static int mvebu_spi_xfer(struct udevice *dev, unsigned int bitlen,
135 			  const void *dout, void *din, unsigned long flags)
136 {
137 	struct udevice *bus = dev->parent;
138 	struct mvebu_spi_platdata *plat = dev_get_platdata(bus);
139 	struct spi_reg *reg = plat->spireg;
140 	unsigned int bytelen;
141 	int ret;
142 
143 	bytelen = bitlen / 8;
144 
145 	if (dout && din)
146 		debug("This is a duplex transfer.\n");
147 
148 	/* Activate CS */
149 	if (flags & SPI_XFER_BEGIN) {
150 		debug("SPI: activate cs.\n");
151 		spi_cs_activate(reg, spi_chip_select(dev));
152 	}
153 
154 	/* Send and/or receive */
155 	if (dout || din) {
156 		ret = spi_legacy_shift_byte(reg, bytelen, dout, din);
157 		if (ret)
158 			return ret;
159 	}
160 
161 	/* Deactivate CS */
162 	if (flags & SPI_XFER_END) {
163 		ret = wait_for_bit(__func__, &reg->ctrl,
164 				   MVEBU_SPI_A3700_XFER_RDY, true, 100, false);
165 		if (ret)
166 			return ret;
167 
168 		debug("SPI: deactivate cs.\n");
169 		spi_cs_deactivate(reg, spi_chip_select(dev));
170 	}
171 
172 	return 0;
173 }
174 
175 static int mvebu_spi_set_speed(struct udevice *bus, uint hz)
176 {
177 	struct mvebu_spi_platdata *plat = dev_get_platdata(bus);
178 	struct spi_reg *reg = plat->spireg;
179 	u32 data;
180 
181 	data = readl(&reg->cfg);
182 
183 	/* Set Prescaler */
184 	data &= ~MVEBU_SPI_A3700_CLK_PRESCALE_MASK;
185 
186 	/* Calculate Prescaler = (spi_input_freq / spi_max_freq) */
187 	if (hz > plat->frequency)
188 		hz = plat->frequency;
189 	data |= plat->clock / hz;
190 
191 	writel(data, &reg->cfg);
192 
193 	return 0;
194 }
195 
196 static int mvebu_spi_set_mode(struct udevice *bus, uint mode)
197 {
198 	struct mvebu_spi_platdata *plat = dev_get_platdata(bus);
199 	struct spi_reg *reg = plat->spireg;
200 
201 	/*
202 	 * Set SPI polarity
203 	 * 0: Serial interface clock is low when inactive
204 	 * 1: Serial interface clock is high when inactive
205 	 */
206 	if (mode & SPI_CPOL)
207 		setbits_le32(&reg->cfg, MVEBU_SPI_A3700_CLK_POL);
208 	else
209 		clrbits_le32(&reg->cfg, MVEBU_SPI_A3700_CLK_POL);
210 	if (mode & SPI_CPHA)
211 		setbits_le32(&reg->cfg, MVEBU_SPI_A3700_CLK_PHA);
212 	else
213 		clrbits_le32(&reg->cfg, MVEBU_SPI_A3700_CLK_PHA);
214 
215 	return 0;
216 }
217 
218 static int mvebu_spi_probe(struct udevice *bus)
219 {
220 	struct mvebu_spi_platdata *plat = dev_get_platdata(bus);
221 	struct spi_reg *reg = plat->spireg;
222 	u32 data;
223 	int ret;
224 
225 	/*
226 	 * Settings SPI controller to be working in legacy mode, which
227 	 * means use only DO pin (I/O 1) for Data Out, and DI pin (I/O 0)
228 	 * for Data In.
229 	 */
230 
231 	/* Flush read/write FIFO */
232 	data = readl(&reg->cfg);
233 	writel(data | MVEBU_SPI_A3700_FIFO_FLUSH, &reg->cfg);
234 	ret = wait_for_bit(__func__, &reg->cfg, MVEBU_SPI_A3700_FIFO_FLUSH,
235 			   false, 1000, false);
236 	if (ret)
237 		return ret;
238 
239 	/* Disable FIFO mode */
240 	data &= ~MVEBU_SPI_A3700_FIFO_EN;
241 
242 	/* Always shift 1 byte at a time */
243 	data &= ~MVEBU_SPI_A3700_BYTE_LEN;
244 
245 	writel(data, &reg->cfg);
246 
247 	return 0;
248 }
249 
250 static int mvebu_spi_ofdata_to_platdata(struct udevice *bus)
251 {
252 	struct mvebu_spi_platdata *plat = dev_get_platdata(bus);
253 
254 	plat->spireg = (struct spi_reg *)dev_get_addr(bus);
255 
256 	/*
257 	 * FIXME
258 	 * Right now, mvebu does not have a clock infrastructure in U-Boot
259 	 * which should be used to query the input clock to the SPI
260 	 * controller. Once this clock driver is integrated into U-Boot
261 	 * it should be used to read the input clock and the DT property
262 	 * can be removed.
263 	 */
264 	plat->clock = fdtdec_get_int(gd->fdt_blob, bus->of_offset,
265 				     "clock-frequency", 160000);
266 	plat->frequency = fdtdec_get_int(gd->fdt_blob, bus->of_offset,
267 					 "spi-max-frequency", 40000);
268 
269 	return 0;
270 }
271 
272 static const struct dm_spi_ops mvebu_spi_ops = {
273 	.xfer		= mvebu_spi_xfer,
274 	.set_speed	= mvebu_spi_set_speed,
275 	.set_mode	= mvebu_spi_set_mode,
276 	/*
277 	 * cs_info is not needed, since we require all chip selects to be
278 	 * in the device tree explicitly
279 	 */
280 };
281 
282 static const struct udevice_id mvebu_spi_ids[] = {
283 	{ .compatible = "marvell,armada-3700-spi" },
284 	{ }
285 };
286 
287 U_BOOT_DRIVER(mvebu_spi) = {
288 	.name = "mvebu_spi",
289 	.id = UCLASS_SPI,
290 	.of_match = mvebu_spi_ids,
291 	.ops = &mvebu_spi_ops,
292 	.ofdata_to_platdata = mvebu_spi_ofdata_to_platdata,
293 	.platdata_auto_alloc_size = sizeof(struct mvebu_spi_platdata),
294 	.probe = mvebu_spi_probe,
295 };
296