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f3e89362 CF |
1 | // SPDX-License-Identifier: (GPL-2.0 OR MIT) |
2 | /* | |
3 | * SPI core driver for the Ocelot chip family. | |
4 | * | |
5 | * This driver will handle everything necessary to allow for communication over | |
6 | * SPI to the VSC7511, VSC7512, VSC7513 and VSC7514 chips. The main functions | |
7 | * are to prepare the chip's SPI interface for a specific bus speed, and a host | |
8 | * processor's endianness. This will create and distribute regmaps for any | |
9 | * children. | |
10 | * | |
11 | * Copyright 2021-2022 Innovative Advantage Inc. | |
12 | * | |
13 | * Author: Colin Foster <colin.foster@in-advantage.com> | |
14 | */ | |
15 | ||
16 | #include <linux/device.h> | |
17 | #include <linux/err.h> | |
18 | #include <linux/errno.h> | |
19 | #include <linux/export.h> | |
20 | #include <linux/ioport.h> | |
21 | #include <linux/mod_devicetable.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/regmap.h> | |
24 | #include <linux/spi/spi.h> | |
25 | #include <linux/types.h> | |
26 | #include <linux/units.h> | |
27 | ||
28 | #include "ocelot.h" | |
29 | ||
30 | #define REG_DEV_CPUORG_IF_CTRL 0x0000 | |
31 | #define REG_DEV_CPUORG_IF_CFGSTAT 0x0004 | |
32 | ||
33 | #define CFGSTAT_IF_NUM_VCORE (0 << 24) | |
34 | #define CFGSTAT_IF_NUM_VRAP (1 << 24) | |
35 | #define CFGSTAT_IF_NUM_SI (2 << 24) | |
36 | #define CFGSTAT_IF_NUM_MIIM (3 << 24) | |
37 | ||
38 | #define VSC7512_DEVCPU_ORG_RES_START 0x71000000 | |
39 | #define VSC7512_DEVCPU_ORG_RES_SIZE 0x38 | |
40 | ||
41 | #define VSC7512_CHIP_REGS_RES_START 0x71070000 | |
42 | #define VSC7512_CHIP_REGS_RES_SIZE 0x14 | |
43 | ||
44 | static const struct resource vsc7512_dev_cpuorg_resource = | |
45 | DEFINE_RES_REG_NAMED(VSC7512_DEVCPU_ORG_RES_START, | |
46 | VSC7512_DEVCPU_ORG_RES_SIZE, | |
47 | "devcpu_org"); | |
48 | ||
49 | static const struct resource vsc7512_gcb_resource = | |
50 | DEFINE_RES_REG_NAMED(VSC7512_CHIP_REGS_RES_START, | |
51 | VSC7512_CHIP_REGS_RES_SIZE, | |
52 | "devcpu_gcb_chip_regs"); | |
53 | ||
54 | static int ocelot_spi_initialize(struct device *dev) | |
55 | { | |
56 | struct ocelot_ddata *ddata = dev_get_drvdata(dev); | |
57 | u32 val, check; | |
58 | int err; | |
59 | ||
60 | val = OCELOT_SPI_BYTE_ORDER; | |
61 | ||
62 | /* | |
63 | * The SPI address must be big-endian, but we want the payload to match | |
64 | * our CPU. These are two bits (0 and 1) but they're repeated such that | |
65 | * the write from any configuration will be valid. The four | |
66 | * configurations are: | |
67 | * | |
68 | * 0b00: little-endian, MSB first | |
69 | * | 111111 | 22221111 | 33222222 | | |
70 | * | 76543210 | 54321098 | 32109876 | 10987654 | | |
71 | * | |
72 | * 0b01: big-endian, MSB first | |
73 | * | 33222222 | 22221111 | 111111 | | | |
74 | * | 10987654 | 32109876 | 54321098 | 76543210 | | |
75 | * | |
76 | * 0b10: little-endian, LSB first | |
77 | * | 111111 | 11112222 | 22222233 | | |
78 | * | 01234567 | 89012345 | 67890123 | 45678901 | | |
79 | * | |
80 | * 0b11: big-endian, LSB first | |
81 | * | 22222233 | 11112222 | 111111 | | | |
82 | * | 45678901 | 67890123 | 89012345 | 01234567 | | |
83 | */ | |
84 | err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CTRL, val); | |
85 | if (err) | |
86 | return err; | |
87 | ||
88 | /* | |
89 | * Apply the number of padding bytes between a read request and the data | |
90 | * payload. Some registers have access times of up to 1us, so if the | |
91 | * first payload bit is shifted out too quickly, the read will fail. | |
92 | */ | |
93 | val = ddata->spi_padding_bytes; | |
94 | err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, val); | |
95 | if (err) | |
96 | return err; | |
97 | ||
98 | /* | |
99 | * After we write the interface configuration, read it back here. This | |
100 | * will verify several different things. The first is that the number of | |
101 | * padding bytes actually got written correctly. These are found in bits | |
102 | * 0:3. | |
103 | * | |
104 | * The second is that bit 16 is cleared. Bit 16 is IF_CFGSTAT:IF_STAT, | |
105 | * and will be set if the register access is too fast. This would be in | |
106 | * the condition that the number of padding bytes is insufficient for | |
107 | * the SPI bus frequency. | |
108 | * | |
109 | * The last check is for bits 31:24, which define the interface by which | |
110 | * the registers are being accessed. Since we're accessing them via the | |
111 | * serial interface, it must return IF_NUM_SI. | |
112 | */ | |
113 | check = val | CFGSTAT_IF_NUM_SI; | |
114 | ||
115 | err = regmap_read(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, &val); | |
116 | if (err) | |
117 | return err; | |
118 | ||
119 | if (check != val) | |
120 | return -ENODEV; | |
121 | ||
122 | return 0; | |
123 | } | |
124 | ||
125 | static const struct regmap_config ocelot_spi_regmap_config = { | |
126 | .reg_bits = 24, | |
127 | .reg_stride = 4, | |
128 | .reg_downshift = 2, | |
129 | .val_bits = 32, | |
130 | ||
131 | .write_flag_mask = 0x80, | |
132 | ||
133 | .use_single_write = true, | |
134 | .can_multi_write = false, | |
135 | ||
136 | .reg_format_endian = REGMAP_ENDIAN_BIG, | |
137 | .val_format_endian = REGMAP_ENDIAN_NATIVE, | |
138 | }; | |
139 | ||
140 | static int ocelot_spi_regmap_bus_read(void *context, const void *reg, size_t reg_size, | |
141 | void *val, size_t val_size) | |
142 | { | |
143 | struct spi_transfer xfers[3] = {0}; | |
144 | struct device *dev = context; | |
145 | struct ocelot_ddata *ddata; | |
146 | struct spi_device *spi; | |
147 | struct spi_message msg; | |
148 | unsigned int index = 0; | |
149 | ||
150 | ddata = dev_get_drvdata(dev); | |
151 | spi = to_spi_device(dev); | |
152 | ||
153 | xfers[index].tx_buf = reg; | |
154 | xfers[index].len = reg_size; | |
155 | index++; | |
156 | ||
157 | if (ddata->spi_padding_bytes) { | |
158 | xfers[index].len = ddata->spi_padding_bytes; | |
159 | xfers[index].tx_buf = ddata->dummy_buf; | |
160 | xfers[index].dummy_data = 1; | |
161 | index++; | |
162 | } | |
163 | ||
164 | xfers[index].rx_buf = val; | |
165 | xfers[index].len = val_size; | |
166 | index++; | |
167 | ||
168 | spi_message_init_with_transfers(&msg, xfers, index); | |
169 | ||
170 | return spi_sync(spi, &msg); | |
171 | } | |
172 | ||
173 | static int ocelot_spi_regmap_bus_write(void *context, const void *data, size_t count) | |
174 | { | |
175 | struct device *dev = context; | |
176 | struct spi_device *spi = to_spi_device(dev); | |
177 | ||
178 | return spi_write(spi, data, count); | |
179 | } | |
180 | ||
181 | static const struct regmap_bus ocelot_spi_regmap_bus = { | |
182 | .write = ocelot_spi_regmap_bus_write, | |
183 | .read = ocelot_spi_regmap_bus_read, | |
184 | }; | |
185 | ||
186 | struct regmap *ocelot_spi_init_regmap(struct device *dev, const struct resource *res) | |
187 | { | |
188 | struct regmap_config regmap_config; | |
189 | ||
190 | memcpy(®map_config, &ocelot_spi_regmap_config, sizeof(regmap_config)); | |
191 | ||
192 | regmap_config.name = res->name; | |
193 | regmap_config.max_register = resource_size(res) - 1; | |
194 | regmap_config.reg_base = res->start; | |
195 | ||
196 | return devm_regmap_init(dev, &ocelot_spi_regmap_bus, dev, ®map_config); | |
197 | } | |
198 | EXPORT_SYMBOL_NS(ocelot_spi_init_regmap, MFD_OCELOT_SPI); | |
199 | ||
200 | static int ocelot_spi_probe(struct spi_device *spi) | |
201 | { | |
202 | struct device *dev = &spi->dev; | |
203 | struct ocelot_ddata *ddata; | |
204 | struct regmap *r; | |
205 | int err; | |
206 | ||
207 | ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL); | |
208 | if (!ddata) | |
209 | return -ENOMEM; | |
210 | ||
211 | spi_set_drvdata(spi, ddata); | |
212 | ||
213 | if (spi->max_speed_hz <= 500000) { | |
214 | ddata->spi_padding_bytes = 0; | |
215 | } else { | |
216 | /* | |
217 | * Calculation taken from the manual for IF_CFGSTAT:IF_CFG. | |
218 | * Register access time is 1us, so we need to configure and send | |
219 | * out enough padding bytes between the read request and data | |
220 | * transmission that lasts at least 1 microsecond. | |
221 | */ | |
222 | ddata->spi_padding_bytes = 1 + (spi->max_speed_hz / HZ_PER_MHZ + 2) / 8; | |
223 | ||
224 | ddata->dummy_buf = devm_kzalloc(dev, ddata->spi_padding_bytes, GFP_KERNEL); | |
225 | if (!ddata->dummy_buf) | |
226 | return -ENOMEM; | |
227 | } | |
228 | ||
229 | spi->bits_per_word = 8; | |
230 | ||
231 | err = spi_setup(spi); | |
232 | if (err) | |
233 | return dev_err_probe(&spi->dev, err, "Error performing SPI setup\n"); | |
234 | ||
235 | r = ocelot_spi_init_regmap(dev, &vsc7512_dev_cpuorg_resource); | |
236 | if (IS_ERR(r)) | |
237 | return PTR_ERR(r); | |
238 | ||
239 | ddata->cpuorg_regmap = r; | |
240 | ||
241 | r = ocelot_spi_init_regmap(dev, &vsc7512_gcb_resource); | |
242 | if (IS_ERR(r)) | |
243 | return PTR_ERR(r); | |
244 | ||
245 | ddata->gcb_regmap = r; | |
246 | ||
247 | /* | |
248 | * The chip must be set up for SPI before it gets initialized and reset. | |
249 | * This must be done before calling init, and after a chip reset is | |
250 | * performed. | |
251 | */ | |
252 | err = ocelot_spi_initialize(dev); | |
253 | if (err) | |
254 | return dev_err_probe(dev, err, "Error initializing SPI bus\n"); | |
255 | ||
256 | err = ocelot_chip_reset(dev); | |
257 | if (err) | |
258 | return dev_err_probe(dev, err, "Error resetting device\n"); | |
259 | ||
260 | /* | |
261 | * A chip reset will clear the SPI configuration, so it needs to be done | |
262 | * again before we can access any registers. | |
263 | */ | |
264 | err = ocelot_spi_initialize(dev); | |
265 | if (err) | |
266 | return dev_err_probe(dev, err, "Error initializing SPI bus after reset\n"); | |
267 | ||
268 | err = ocelot_core_init(dev); | |
269 | if (err) | |
270 | return dev_err_probe(dev, err, "Error initializing Ocelot core\n"); | |
271 | ||
272 | return 0; | |
273 | } | |
274 | ||
275 | static const struct spi_device_id ocelot_spi_ids[] = { | |
276 | { "vsc7512", 0 }, | |
277 | { } | |
278 | }; | |
02010cf0 | 279 | MODULE_DEVICE_TABLE(spi, ocelot_spi_ids); |
f3e89362 CF |
280 | |
281 | static const struct of_device_id ocelot_spi_of_match[] = { | |
282 | { .compatible = "mscc,vsc7512" }, | |
283 | { } | |
284 | }; | |
285 | MODULE_DEVICE_TABLE(of, ocelot_spi_of_match); | |
286 | ||
287 | static struct spi_driver ocelot_spi_driver = { | |
288 | .driver = { | |
289 | .name = "ocelot-soc", | |
290 | .of_match_table = ocelot_spi_of_match, | |
291 | }, | |
292 | .id_table = ocelot_spi_ids, | |
293 | .probe = ocelot_spi_probe, | |
294 | }; | |
295 | module_spi_driver(ocelot_spi_driver); | |
296 | ||
297 | MODULE_DESCRIPTION("SPI Controlled Ocelot Chip Driver"); | |
298 | MODULE_AUTHOR("Colin Foster <colin.foster@in-advantage.com>"); | |
299 | MODULE_LICENSE("Dual MIT/GPL"); | |
300 | MODULE_IMPORT_NS(MFD_OCELOT); |