1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * NXP LPC18xx/LPC43xx EEPROM memory NVMEM driver
4 *
5 * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
6 */
7
8 #include <linux/clk.h>
9 #include <linux/device.h>
10 #include <linux/delay.h>
11 #include <linux/err.h>
12 #include <linux/io.h>
13 #include <linux/module.h>
14 #include <linux/mod_devicetable.h>
15 #include <linux/nvmem-provider.h>
16 #include <linux/platform_device.h>
17 #include <linux/reset.h>
18
19 /* Registers */
20 #define LPC18XX_EEPROM_AUTOPROG 0x00c
21 #define LPC18XX_EEPROM_AUTOPROG_WORD 0x1
22
23 #define LPC18XX_EEPROM_CLKDIV 0x014
24
25 #define LPC18XX_EEPROM_PWRDWN 0x018
26 #define LPC18XX_EEPROM_PWRDWN_NO 0x0
27 #define LPC18XX_EEPROM_PWRDWN_YES 0x1
28
29 #define LPC18XX_EEPROM_INTSTAT 0xfe0
30 #define LPC18XX_EEPROM_INTSTAT_END_OF_PROG BIT(2)
31
32 #define LPC18XX_EEPROM_INTSTATCLR 0xfe8
33 #define LPC18XX_EEPROM_INTSTATCLR_PROG_CLR_ST BIT(2)
34
35 /* Fixed page size (bytes) */
36 #define LPC18XX_EEPROM_PAGE_SIZE 0x80
37
38 /* EEPROM device requires a ~1500 kHz clock (min 800 kHz, max 1600 kHz) */
39 #define LPC18XX_EEPROM_CLOCK_HZ 1500000
40
41 /* EEPROM requires 3 ms of erase/program time between each writing */
42 #define LPC18XX_EEPROM_PROGRAM_TIME 3
43
44 struct lpc18xx_eeprom_dev {
45 struct clk *clk;
46 void __iomem *reg_base;
47 void __iomem *mem_base;
48 struct nvmem_device *nvmem;
49 unsigned reg_bytes;
50 unsigned val_bytes;
51 int size;
52 };
53
lpc18xx_eeprom_writel(struct lpc18xx_eeprom_dev * eeprom,u32 reg,u32 val)54 static inline void lpc18xx_eeprom_writel(struct lpc18xx_eeprom_dev *eeprom,
55 u32 reg, u32 val)
56 {
57 writel(val, eeprom->reg_base + reg);
58 }
59
lpc18xx_eeprom_readl(struct lpc18xx_eeprom_dev * eeprom,u32 reg)60 static inline u32 lpc18xx_eeprom_readl(struct lpc18xx_eeprom_dev *eeprom,
61 u32 reg)
62 {
63 return readl(eeprom->reg_base + reg);
64 }
65
lpc18xx_eeprom_busywait_until_prog(struct lpc18xx_eeprom_dev * eeprom)66 static int lpc18xx_eeprom_busywait_until_prog(struct lpc18xx_eeprom_dev *eeprom)
67 {
68 unsigned long end;
69 u32 val;
70
71 /* Wait until EEPROM program operation has finished */
72 end = jiffies + msecs_to_jiffies(LPC18XX_EEPROM_PROGRAM_TIME * 10);
73
74 while (time_is_after_jiffies(end)) {
75 val = lpc18xx_eeprom_readl(eeprom, LPC18XX_EEPROM_INTSTAT);
76
77 if (val & LPC18XX_EEPROM_INTSTAT_END_OF_PROG) {
78 lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_INTSTATCLR,
79 LPC18XX_EEPROM_INTSTATCLR_PROG_CLR_ST);
80 return 0;
81 }
82
83 usleep_range(LPC18XX_EEPROM_PROGRAM_TIME * USEC_PER_MSEC,
84 (LPC18XX_EEPROM_PROGRAM_TIME + 1) * USEC_PER_MSEC);
85 }
86
87 return -ETIMEDOUT;
88 }
89
lpc18xx_eeprom_gather_write(void * context,unsigned int reg,void * val,size_t bytes)90 static int lpc18xx_eeprom_gather_write(void *context, unsigned int reg,
91 void *val, size_t bytes)
92 {
93 struct lpc18xx_eeprom_dev *eeprom = context;
94 unsigned int offset = reg;
95 int ret;
96
97 /*
98 * The last page contains the EEPROM initialization data and is not
99 * writable.
100 */
101 if ((reg > eeprom->size - LPC18XX_EEPROM_PAGE_SIZE) ||
102 (reg + bytes > eeprom->size - LPC18XX_EEPROM_PAGE_SIZE))
103 return -EINVAL;
104
105
106 lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
107 LPC18XX_EEPROM_PWRDWN_NO);
108
109 /* Wait 100 us while the EEPROM wakes up */
110 usleep_range(100, 200);
111
112 while (bytes) {
113 writel(*(u32 *)val, eeprom->mem_base + offset);
114 ret = lpc18xx_eeprom_busywait_until_prog(eeprom);
115 if (ret < 0)
116 return ret;
117
118 bytes -= eeprom->val_bytes;
119 val += eeprom->val_bytes;
120 offset += eeprom->val_bytes;
121 }
122
123 lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
124 LPC18XX_EEPROM_PWRDWN_YES);
125
126 return 0;
127 }
128
lpc18xx_eeprom_read(void * context,unsigned int offset,void * val,size_t bytes)129 static int lpc18xx_eeprom_read(void *context, unsigned int offset,
130 void *val, size_t bytes)
131 {
132 struct lpc18xx_eeprom_dev *eeprom = context;
133
134 lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
135 LPC18XX_EEPROM_PWRDWN_NO);
136
137 /* Wait 100 us while the EEPROM wakes up */
138 usleep_range(100, 200);
139
140 while (bytes) {
141 *(u32 *)val = readl(eeprom->mem_base + offset);
142 bytes -= eeprom->val_bytes;
143 val += eeprom->val_bytes;
144 offset += eeprom->val_bytes;
145 }
146
147 lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
148 LPC18XX_EEPROM_PWRDWN_YES);
149
150 return 0;
151 }
152
153
154 static struct nvmem_config lpc18xx_nvmem_config = {
155 .name = "lpc18xx-eeprom",
156 .stride = 4,
157 .word_size = 4,
158 .reg_read = lpc18xx_eeprom_read,
159 .reg_write = lpc18xx_eeprom_gather_write,
160 };
161
lpc18xx_eeprom_probe(struct platform_device * pdev)162 static int lpc18xx_eeprom_probe(struct platform_device *pdev)
163 {
164 struct lpc18xx_eeprom_dev *eeprom;
165 struct device *dev = &pdev->dev;
166 struct reset_control *rst;
167 unsigned long clk_rate;
168 struct resource *res;
169 int ret;
170
171 eeprom = devm_kzalloc(dev, sizeof(*eeprom), GFP_KERNEL);
172 if (!eeprom)
173 return -ENOMEM;
174
175 res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "reg");
176 eeprom->reg_base = devm_ioremap_resource(dev, res);
177 if (IS_ERR(eeprom->reg_base))
178 return PTR_ERR(eeprom->reg_base);
179
180 res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mem");
181 eeprom->mem_base = devm_ioremap_resource(dev, res);
182 if (IS_ERR(eeprom->mem_base))
183 return PTR_ERR(eeprom->mem_base);
184
185 eeprom->clk = devm_clk_get(&pdev->dev, "eeprom");
186 if (IS_ERR(eeprom->clk)) {
187 dev_err(&pdev->dev, "failed to get eeprom clock\n");
188 return PTR_ERR(eeprom->clk);
189 }
190
191 ret = clk_prepare_enable(eeprom->clk);
192 if (ret < 0) {
193 dev_err(dev, "failed to prepare/enable eeprom clk: %d\n", ret);
194 return ret;
195 }
196
197 rst = devm_reset_control_get_exclusive(dev, NULL);
198 if (IS_ERR(rst)) {
199 dev_err(dev, "failed to get reset: %ld\n", PTR_ERR(rst));
200 ret = PTR_ERR(rst);
201 goto err_clk;
202 }
203
204 ret = reset_control_assert(rst);
205 if (ret < 0) {
206 dev_err(dev, "failed to assert reset: %d\n", ret);
207 goto err_clk;
208 }
209
210 eeprom->val_bytes = 4;
211 eeprom->reg_bytes = 4;
212
213 /*
214 * Clock rate is generated by dividing the system bus clock by the
215 * division factor, contained in the divider register (minus 1 encoded).
216 */
217 clk_rate = clk_get_rate(eeprom->clk);
218 clk_rate = DIV_ROUND_UP(clk_rate, LPC18XX_EEPROM_CLOCK_HZ) - 1;
219 lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_CLKDIV, clk_rate);
220
221 /*
222 * Writing a single word to the page will start the erase/program cycle
223 * automatically
224 */
225 lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_AUTOPROG,
226 LPC18XX_EEPROM_AUTOPROG_WORD);
227
228 lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
229 LPC18XX_EEPROM_PWRDWN_YES);
230
231 eeprom->size = resource_size(res);
232 lpc18xx_nvmem_config.size = resource_size(res);
233 lpc18xx_nvmem_config.dev = dev;
234 lpc18xx_nvmem_config.priv = eeprom;
235
236 eeprom->nvmem = devm_nvmem_register(dev, &lpc18xx_nvmem_config);
237 if (IS_ERR(eeprom->nvmem)) {
238 ret = PTR_ERR(eeprom->nvmem);
239 goto err_clk;
240 }
241
242 platform_set_drvdata(pdev, eeprom);
243
244 return 0;
245
246 err_clk:
247 clk_disable_unprepare(eeprom->clk);
248
249 return ret;
250 }
251
lpc18xx_eeprom_remove(struct platform_device * pdev)252 static int lpc18xx_eeprom_remove(struct platform_device *pdev)
253 {
254 struct lpc18xx_eeprom_dev *eeprom = platform_get_drvdata(pdev);
255
256 clk_disable_unprepare(eeprom->clk);
257
258 return 0;
259 }
260
261 static const struct of_device_id lpc18xx_eeprom_of_match[] = {
262 { .compatible = "nxp,lpc1857-eeprom" },
263 { },
264 };
265 MODULE_DEVICE_TABLE(of, lpc18xx_eeprom_of_match);
266
267 static struct platform_driver lpc18xx_eeprom_driver = {
268 .probe = lpc18xx_eeprom_probe,
269 .remove = lpc18xx_eeprom_remove,
270 .driver = {
271 .name = "lpc18xx-eeprom",
272 .of_match_table = lpc18xx_eeprom_of_match,
273 },
274 };
275
276 module_platform_driver(lpc18xx_eeprom_driver);
277
278 MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
279 MODULE_DESCRIPTION("NXP LPC18xx EEPROM memory Driver");
280 MODULE_LICENSE("GPL v2");
281
