1 /*
2  * NXP LPC18xx/LPC43xx EEPROM memory NVMEM driver
3  *
4  * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License version 2 as published by
8  * the Free Software Foundation.
9  */
10 
11 #include <linux/clk.h>
12 #include <linux/device.h>
13 #include <linux/delay.h>
14 #include <linux/err.h>
15 #include <linux/io.h>
16 #include <linux/module.h>
17 #include <linux/mod_devicetable.h>
18 #include <linux/nvmem-provider.h>
19 #include <linux/platform_device.h>
20 #include <linux/reset.h>
21 
22 /* Registers */
23 #define LPC18XX_EEPROM_AUTOPROG			0x00c
24 #define LPC18XX_EEPROM_AUTOPROG_WORD		0x1
25 
26 #define LPC18XX_EEPROM_CLKDIV			0x014
27 
28 #define LPC18XX_EEPROM_PWRDWN			0x018
29 #define LPC18XX_EEPROM_PWRDWN_NO		0x0
30 #define LPC18XX_EEPROM_PWRDWN_YES		0x1
31 
32 #define LPC18XX_EEPROM_INTSTAT			0xfe0
33 #define LPC18XX_EEPROM_INTSTAT_END_OF_PROG	BIT(2)
34 
35 #define LPC18XX_EEPROM_INTSTATCLR		0xfe8
36 #define LPC18XX_EEPROM_INTSTATCLR_PROG_CLR_ST	BIT(2)
37 
38 /* Fixed page size (bytes) */
39 #define LPC18XX_EEPROM_PAGE_SIZE		0x80
40 
41 /* EEPROM device requires a ~1500 kHz clock (min 800 kHz, max 1600 kHz) */
42 #define LPC18XX_EEPROM_CLOCK_HZ			1500000
43 
44 /* EEPROM requires 3 ms of erase/program time between each writing */
45 #define LPC18XX_EEPROM_PROGRAM_TIME		3
46 
47 struct lpc18xx_eeprom_dev {
48 	struct clk *clk;
49 	void __iomem *reg_base;
50 	void __iomem *mem_base;
51 	struct nvmem_device *nvmem;
52 	unsigned reg_bytes;
53 	unsigned val_bytes;
54 	int size;
55 };
56 
57 static inline void lpc18xx_eeprom_writel(struct lpc18xx_eeprom_dev *eeprom,
58 					 u32 reg, u32 val)
59 {
60 	writel(val, eeprom->reg_base + reg);
61 }
62 
63 static inline u32 lpc18xx_eeprom_readl(struct lpc18xx_eeprom_dev *eeprom,
64 				       u32 reg)
65 {
66 	return readl(eeprom->reg_base + reg);
67 }
68 
69 static int lpc18xx_eeprom_busywait_until_prog(struct lpc18xx_eeprom_dev *eeprom)
70 {
71 	unsigned long end;
72 	u32 val;
73 
74 	/* Wait until EEPROM program operation has finished */
75 	end = jiffies + msecs_to_jiffies(LPC18XX_EEPROM_PROGRAM_TIME * 10);
76 
77 	while (time_is_after_jiffies(end)) {
78 		val = lpc18xx_eeprom_readl(eeprom, LPC18XX_EEPROM_INTSTAT);
79 
80 		if (val & LPC18XX_EEPROM_INTSTAT_END_OF_PROG) {
81 			lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_INTSTATCLR,
82 					LPC18XX_EEPROM_INTSTATCLR_PROG_CLR_ST);
83 			return 0;
84 		}
85 
86 		usleep_range(LPC18XX_EEPROM_PROGRAM_TIME * USEC_PER_MSEC,
87 			     (LPC18XX_EEPROM_PROGRAM_TIME + 1) * USEC_PER_MSEC);
88 	}
89 
90 	return -ETIMEDOUT;
91 }
92 
93 static int lpc18xx_eeprom_gather_write(void *context, unsigned int reg,
94 				       void *val, size_t bytes)
95 {
96 	struct lpc18xx_eeprom_dev *eeprom = context;
97 	unsigned int offset = reg;
98 	int ret;
99 
100 	/*
101 	 * The last page contains the EEPROM initialization data and is not
102 	 * writable.
103 	 */
104 	if ((reg > eeprom->size - LPC18XX_EEPROM_PAGE_SIZE) ||
105 			(reg + bytes > eeprom->size - LPC18XX_EEPROM_PAGE_SIZE))
106 		return -EINVAL;
107 
108 
109 	lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
110 			      LPC18XX_EEPROM_PWRDWN_NO);
111 
112 	/* Wait 100 us while the EEPROM wakes up */
113 	usleep_range(100, 200);
114 
115 	while (bytes) {
116 		writel(*(u32 *)val, eeprom->mem_base + offset);
117 		ret = lpc18xx_eeprom_busywait_until_prog(eeprom);
118 		if (ret < 0)
119 			return ret;
120 
121 		bytes -= eeprom->val_bytes;
122 		val += eeprom->val_bytes;
123 		offset += eeprom->val_bytes;
124 	}
125 
126 	lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
127 			      LPC18XX_EEPROM_PWRDWN_YES);
128 
129 	return 0;
130 }
131 
132 static int lpc18xx_eeprom_read(void *context, unsigned int offset,
133 			       void *val, size_t bytes)
134 {
135 	struct lpc18xx_eeprom_dev *eeprom = context;
136 
137 	lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
138 			      LPC18XX_EEPROM_PWRDWN_NO);
139 
140 	/* Wait 100 us while the EEPROM wakes up */
141 	usleep_range(100, 200);
142 
143 	while (bytes) {
144 		*(u32 *)val = readl(eeprom->mem_base + offset);
145 		bytes -= eeprom->val_bytes;
146 		val += eeprom->val_bytes;
147 		offset += eeprom->val_bytes;
148 	}
149 
150 	lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
151 			      LPC18XX_EEPROM_PWRDWN_YES);
152 
153 	return 0;
154 }
155 
156 
157 static struct nvmem_config lpc18xx_nvmem_config = {
158 	.name = "lpc18xx-eeprom",
159 	.stride = 4,
160 	.word_size = 4,
161 	.reg_read = lpc18xx_eeprom_read,
162 	.reg_write = lpc18xx_eeprom_gather_write,
163 };
164 
165 static int lpc18xx_eeprom_probe(struct platform_device *pdev)
166 {
167 	struct lpc18xx_eeprom_dev *eeprom;
168 	struct device *dev = &pdev->dev;
169 	struct reset_control *rst;
170 	unsigned long clk_rate;
171 	struct resource *res;
172 	int ret;
173 
174 	eeprom = devm_kzalloc(dev, sizeof(*eeprom), GFP_KERNEL);
175 	if (!eeprom)
176 		return -ENOMEM;
177 
178 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "reg");
179 	eeprom->reg_base = devm_ioremap_resource(dev, res);
180 	if (IS_ERR(eeprom->reg_base))
181 		return PTR_ERR(eeprom->reg_base);
182 
183 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mem");
184 	eeprom->mem_base = devm_ioremap_resource(dev, res);
185 	if (IS_ERR(eeprom->mem_base))
186 		return PTR_ERR(eeprom->mem_base);
187 
188 	eeprom->clk = devm_clk_get(&pdev->dev, "eeprom");
189 	if (IS_ERR(eeprom->clk)) {
190 		dev_err(&pdev->dev, "failed to get eeprom clock\n");
191 		return PTR_ERR(eeprom->clk);
192 	}
193 
194 	ret = clk_prepare_enable(eeprom->clk);
195 	if (ret < 0) {
196 		dev_err(dev, "failed to prepare/enable eeprom clk: %d\n", ret);
197 		return ret;
198 	}
199 
200 	rst = devm_reset_control_get_exclusive(dev, NULL);
201 	if (IS_ERR(rst)) {
202 		dev_err(dev, "failed to get reset: %ld\n", PTR_ERR(rst));
203 		ret = PTR_ERR(rst);
204 		goto err_clk;
205 	}
206 
207 	ret = reset_control_assert(rst);
208 	if (ret < 0) {
209 		dev_err(dev, "failed to assert reset: %d\n", ret);
210 		goto err_clk;
211 	}
212 
213 	eeprom->val_bytes = 4;
214 	eeprom->reg_bytes = 4;
215 
216 	/*
217 	 * Clock rate is generated by dividing the system bus clock by the
218 	 * division factor, contained in the divider register (minus 1 encoded).
219 	 */
220 	clk_rate = clk_get_rate(eeprom->clk);
221 	clk_rate = DIV_ROUND_UP(clk_rate, LPC18XX_EEPROM_CLOCK_HZ) - 1;
222 	lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_CLKDIV, clk_rate);
223 
224 	/*
225 	 * Writing a single word to the page will start the erase/program cycle
226 	 * automatically
227 	 */
228 	lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_AUTOPROG,
229 			      LPC18XX_EEPROM_AUTOPROG_WORD);
230 
231 	lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN,
232 			      LPC18XX_EEPROM_PWRDWN_YES);
233 
234 	eeprom->size = resource_size(res);
235 	lpc18xx_nvmem_config.size = resource_size(res);
236 	lpc18xx_nvmem_config.dev = dev;
237 	lpc18xx_nvmem_config.priv = eeprom;
238 
239 	eeprom->nvmem = nvmem_register(&lpc18xx_nvmem_config);
240 	if (IS_ERR(eeprom->nvmem)) {
241 		ret = PTR_ERR(eeprom->nvmem);
242 		goto err_clk;
243 	}
244 
245 	platform_set_drvdata(pdev, eeprom);
246 
247 	return 0;
248 
249 err_clk:
250 	clk_disable_unprepare(eeprom->clk);
251 
252 	return ret;
253 }
254 
255 static int lpc18xx_eeprom_remove(struct platform_device *pdev)
256 {
257 	struct lpc18xx_eeprom_dev *eeprom = platform_get_drvdata(pdev);
258 	int ret;
259 
260 	ret = nvmem_unregister(eeprom->nvmem);
261 	if (ret < 0)
262 		return ret;
263 
264 	clk_disable_unprepare(eeprom->clk);
265 
266 	return 0;
267 }
268 
269 static const struct of_device_id lpc18xx_eeprom_of_match[] = {
270 	{ .compatible = "nxp,lpc1857-eeprom" },
271 	{ },
272 };
273 MODULE_DEVICE_TABLE(of, lpc18xx_eeprom_of_match);
274 
275 static struct platform_driver lpc18xx_eeprom_driver = {
276 	.probe = lpc18xx_eeprom_probe,
277 	.remove = lpc18xx_eeprom_remove,
278 	.driver = {
279 		.name = "lpc18xx-eeprom",
280 		.of_match_table = lpc18xx_eeprom_of_match,
281 	},
282 };
283 
284 module_platform_driver(lpc18xx_eeprom_driver);
285 
286 MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
287 MODULE_DESCRIPTION("NXP LPC18xx EEPROM memory Driver");
288 MODULE_LICENSE("GPL v2");
289