1/*
2 * Copyright (C) 2016 Broadcom
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation version 2.
7 *
8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
9 * kind, whether express or implied; without even the implied warranty
10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 */
13
14#include <linux/acpi.h>
15#include <linux/delay.h>
16#include <linux/device.h>
17#include <linux/io.h>
18#include <linux/module.h>
19#include <linux/nvmem-provider.h>
20#include <linux/of.h>
21#include <linux/of_device.h>
22#include <linux/platform_device.h>
23
24/*
25 * # of tries for OTP Status. The time to execute a command varies. The slowest
26 * commands are writes which also vary based on the # of bits turned on. Writing
27 * 0xffffffff takes ~3800 us.
28 */
29#define OTPC_RETRIES 5000
30
31/* Sequence to enable OTP program */
32#define OTPC_PROG_EN_SEQ { 0xf, 0x4, 0x8, 0xd }
33
34/* OTPC Commands */
35#define OTPC_CMD_READ 0x0
36#define OTPC_CMD_OTP_PROG_ENABLE 0x2
37#define OTPC_CMD_OTP_PROG_DISABLE 0x3
38#define OTPC_CMD_PROGRAM 0x8
39
40/* OTPC Status Bits */
41#define OTPC_STAT_CMD_DONE BIT(1)
42#define OTPC_STAT_PROG_OK BIT(2)
43
44/* OTPC register definition */
45#define OTPC_MODE_REG_OFFSET 0x0
46#define OTPC_MODE_REG_OTPC_MODE 0
47#define OTPC_COMMAND_OFFSET 0x4
48#define OTPC_COMMAND_COMMAND_WIDTH 6
49#define OTPC_CMD_START_OFFSET 0x8
50#define OTPC_CMD_START_START 0
51#define OTPC_CPU_STATUS_OFFSET 0xc
52#define OTPC_CPUADDR_REG_OFFSET 0x28
53#define OTPC_CPUADDR_REG_OTPC_CPU_ADDRESS_WIDTH 16
54#define OTPC_CPU_WRITE_REG_OFFSET 0x2c
55
56#define OTPC_CMD_MASK (BIT(OTPC_COMMAND_COMMAND_WIDTH) - 1)
57#define OTPC_ADDR_MASK (BIT(OTPC_CPUADDR_REG_OTPC_CPU_ADDRESS_WIDTH) - 1)
58
59
60struct otpc_map {
61 /* in words. */
62 u32 otpc_row_size;
63 /* 128 bit row / 4 words support. */
64 u16 data_r_offset[4];
65 /* 128 bit row / 4 words support. */
66 u16 data_w_offset[4];
67};
68
69static struct otpc_map otp_map = {
70 .otpc_row_size = 1,
71 .data_r_offset = {0x10},
72 .data_w_offset = {0x2c},
73};
74
75static struct otpc_map otp_map_v2 = {
76 .otpc_row_size = 2,
77 .data_r_offset = {0x10, 0x5c},
78 .data_w_offset = {0x2c, 0x64},
79};
80
81struct otpc_priv {
82 struct device *dev;
83 void __iomem *base;
84 const struct otpc_map *map;
85 struct nvmem_config *config;
86};
87
88static inline void set_command(void __iomem *base, u32 command)
89{
90 writel(command & OTPC_CMD_MASK, base + OTPC_COMMAND_OFFSET);
91}
92
93static inline void set_cpu_address(void __iomem *base, u32 addr)
94{
95 writel(addr & OTPC_ADDR_MASK, base + OTPC_CPUADDR_REG_OFFSET);
96}
97
98static inline void set_start_bit(void __iomem *base)
99{
100 writel(1 << OTPC_CMD_START_START, base + OTPC_CMD_START_OFFSET);
101}
102
103static inline void reset_start_bit(void __iomem *base)
104{
105 writel(0, base + OTPC_CMD_START_OFFSET);
106}
107
108static inline void write_cpu_data(void __iomem *base, u32 value)
109{
110 writel(value, base + OTPC_CPU_WRITE_REG_OFFSET);
111}
112
113static int poll_cpu_status(void __iomem *base, u32 value)
114{
115 u32 status;
116 u32 retries;
117
118 for (retries = 0; retries < OTPC_RETRIES; retries++) {
119 status = readl(base + OTPC_CPU_STATUS_OFFSET);
120 if (status & value)
121 break;
122 udelay(1);
123 }
124 if (retries == OTPC_RETRIES)
125 return -EAGAIN;
126
127 return 0;
128}
129
130static int enable_ocotp_program(void __iomem *base)
131{
132 static const u32 vals[] = OTPC_PROG_EN_SEQ;
133 int i;
134 int ret;
135
136 /* Write the magic sequence to enable programming */
137 set_command(base, OTPC_CMD_OTP_PROG_ENABLE);
138 for (i = 0; i < ARRAY_SIZE(vals); i++) {
139 write_cpu_data(base, vals[i]);
140 set_start_bit(base);
141 ret = poll_cpu_status(base, OTPC_STAT_CMD_DONE);
142 reset_start_bit(base);
143 if (ret)
144 return ret;
145 }
146
147 return poll_cpu_status(base, OTPC_STAT_PROG_OK);
148}
149
150static int disable_ocotp_program(void __iomem *base)
151{
152 int ret;
153
154 set_command(base, OTPC_CMD_OTP_PROG_DISABLE);
155 set_start_bit(base);
156 ret = poll_cpu_status(base, OTPC_STAT_PROG_OK);
157 reset_start_bit(base);
158
159 return ret;
160}
161
162static int bcm_otpc_read(void *context, unsigned int offset, void *val,
163 size_t bytes)
164{
165 struct otpc_priv *priv = context;
166 u32 *buf = val;
167 u32 bytes_read;
168 u32 address = offset / priv->config->word_size;
169 int i, ret;
170
171 for (bytes_read = 0; bytes_read < bytes;) {
172 set_command(priv->base, OTPC_CMD_READ);
173 set_cpu_address(priv->base, address++);
174 set_start_bit(priv->base);
175 ret = poll_cpu_status(priv->base, OTPC_STAT_CMD_DONE);
176 if (ret) {
177 dev_err(priv->dev, "otp read error: 0x%x", ret);
178 return -EIO;
179 }
180
181 for (i = 0; i < priv->map->otpc_row_size; i++) {
182 *buf++ = readl(priv->base +
183 priv->map->data_r_offset[i]);
184 bytes_read += sizeof(*buf);
185 }
186
187 reset_start_bit(priv->base);
188 }
189
190 return 0;
191}
192
193static int bcm_otpc_write(void *context, unsigned int offset, void *val,
194 size_t bytes)
195{
196 struct otpc_priv *priv = context;
197 u32 *buf = val;
198 u32 bytes_written;
199 u32 address = offset / priv->config->word_size;
200 int i, ret;
201
202 if (offset % priv->config->word_size)
203 return -EINVAL;
204
205 ret = enable_ocotp_program(priv->base);
206 if (ret)
207 return -EIO;
208
209 for (bytes_written = 0; bytes_written < bytes;) {
210 set_command(priv->base, OTPC_CMD_PROGRAM);
211 set_cpu_address(priv->base, address++);
212 for (i = 0; i < priv->map->otpc_row_size; i++) {
213 writel(*buf, priv->base + priv->map->data_w_offset[i]);
214 buf++;
215 bytes_written += sizeof(*buf);
216 }
217 set_start_bit(priv->base);
218 ret = poll_cpu_status(priv->base, OTPC_STAT_CMD_DONE);
219 reset_start_bit(priv->base);
220 if (ret) {
221 dev_err(priv->dev, "otp write error: 0x%x", ret);
222 return -EIO;
223 }
224 }
225
226 disable_ocotp_program(priv->base);
227
228 return 0;
229}
230
231static struct nvmem_config bcm_otpc_nvmem_config = {
232 .name = "bcm-ocotp",
233 .read_only = false,
234 .word_size = 4,
235 .stride = 4,
236 .reg_read = bcm_otpc_read,
237 .reg_write = bcm_otpc_write,
238};
239
240static const struct of_device_id bcm_otpc_dt_ids[] = {
241 { .compatible = "brcm,ocotp", .data = &otp_map },
242 { .compatible = "brcm,ocotp-v2", .data = &otp_map_v2 },
243 { },
244};
245MODULE_DEVICE_TABLE(of, bcm_otpc_dt_ids);
246
247static const struct acpi_device_id bcm_otpc_acpi_ids[] = {
248 { .id = "BRCM0700", .driver_data = (kernel_ulong_t)&otp_map },
249 { .id = "BRCM0701", .driver_data = (kernel_ulong_t)&otp_map_v2 },
250 { /* sentinel */ }
251};
252MODULE_DEVICE_TABLE(acpi, bcm_otpc_acpi_ids);
253
254static int bcm_otpc_probe(struct platform_device *pdev)
255{
256 struct device *dev = &pdev->dev;
257 struct resource *res;
258 struct otpc_priv *priv;
259 struct nvmem_device *nvmem;
260 int err;
261 u32 num_words;
262
263 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
264 if (!priv)
265 return -ENOMEM;
266
267 priv->map = device_get_match_data(dev);
268 if (!priv->map)
269 return -ENODEV;
270
271 /* Get OTP base address register. */
272 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
273 priv->base = devm_ioremap_resource(dev, res);
274 if (IS_ERR(priv->base)) {
275 dev_err(dev, "unable to map I/O memory\n");
276 return PTR_ERR(priv->base);
277 }
278
279 /* Enable CPU access to OTPC. */
280 writel(readl(priv->base + OTPC_MODE_REG_OFFSET) |
281 BIT(OTPC_MODE_REG_OTPC_MODE),
282 priv->base + OTPC_MODE_REG_OFFSET);
283 reset_start_bit(priv->base);
284
285 /* Read size of memory in words. */
286 err = device_property_read_u32(dev, "brcm,ocotp-size", &num_words);
287 if (err) {
288 dev_err(dev, "size parameter not specified\n");
289 return -EINVAL;
290 } else if (num_words == 0) {
291 dev_err(dev, "size must be > 0\n");
292 return -EINVAL;
293 }
294
295 bcm_otpc_nvmem_config.size = 4 * num_words;
296 bcm_otpc_nvmem_config.dev = dev;
297 bcm_otpc_nvmem_config.priv = priv;
298
299 if (priv->map == &otp_map_v2) {
300 bcm_otpc_nvmem_config.word_size = 8;
301 bcm_otpc_nvmem_config.stride = 8;
302 }
303
304 priv->config = &bcm_otpc_nvmem_config;
305
306 nvmem = devm_nvmem_register(dev, &bcm_otpc_nvmem_config);
307 if (IS_ERR(nvmem)) {
308 dev_err(dev, "error registering nvmem config\n");
309 return PTR_ERR(nvmem);
310 }
311
312 return 0;
313}
314
315static struct platform_driver bcm_otpc_driver = {
316 .probe = bcm_otpc_probe,
317 .driver = {
318 .name = "brcm-otpc",
319 .of_match_table = bcm_otpc_dt_ids,
320 .acpi_match_table = ACPI_PTR(bcm_otpc_acpi_ids),
321 },
322};
323module_platform_driver(bcm_otpc_driver);
324
325MODULE_DESCRIPTION("Broadcom OTPC driver");
326MODULE_LICENSE("GPL v2");
327