Commit | Line | Data |
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8f91fc56 JH |
1 | /* |
2 | * PIC32 watchdog driver | |
3 | * | |
4 | * Joshua Henderson <joshua.henderson@microchip.com> | |
5 | * Copyright (c) 2016, Microchip Technology Inc. | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version | |
10 | * 2 of the License, or (at your option) any later version. | |
11 | */ | |
12 | #include <linux/clk.h> | |
13 | #include <linux/device.h> | |
14 | #include <linux/err.h> | |
15 | #include <linux/io.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/of.h> | |
19 | #include <linux/of_device.h> | |
20 | #include <linux/platform_device.h> | |
21 | #include <linux/pm.h> | |
22 | #include <linux/watchdog.h> | |
23 | ||
24 | #include <asm/mach-pic32/pic32.h> | |
25 | ||
26 | /* Watchdog Timer Registers */ | |
27 | #define WDTCON_REG 0x00 | |
28 | ||
29 | /* Watchdog Timer Control Register fields */ | |
30 | #define WDTCON_WIN_EN BIT(0) | |
31 | #define WDTCON_RMCS_MASK 0x0003 | |
32 | #define WDTCON_RMCS_SHIFT 0x0006 | |
33 | #define WDTCON_RMPS_MASK 0x001F | |
34 | #define WDTCON_RMPS_SHIFT 0x0008 | |
35 | #define WDTCON_ON BIT(15) | |
36 | #define WDTCON_CLR_KEY 0x5743 | |
37 | ||
38 | /* Reset Control Register fields for watchdog */ | |
39 | #define RESETCON_TIMEOUT_IDLE BIT(2) | |
40 | #define RESETCON_TIMEOUT_SLEEP BIT(3) | |
41 | #define RESETCON_WDT_TIMEOUT BIT(4) | |
42 | ||
43 | struct pic32_wdt { | |
44 | void __iomem *regs; | |
45 | void __iomem *rst_base; | |
46 | struct clk *clk; | |
47 | }; | |
48 | ||
49 | static inline bool pic32_wdt_is_win_enabled(struct pic32_wdt *wdt) | |
50 | { | |
51 | return !!(readl(wdt->regs + WDTCON_REG) & WDTCON_WIN_EN); | |
52 | } | |
53 | ||
54 | static inline u32 pic32_wdt_get_post_scaler(struct pic32_wdt *wdt) | |
55 | { | |
56 | u32 v = readl(wdt->regs + WDTCON_REG); | |
57 | ||
58 | return (v >> WDTCON_RMPS_SHIFT) & WDTCON_RMPS_MASK; | |
59 | } | |
60 | ||
61 | static inline u32 pic32_wdt_get_clk_id(struct pic32_wdt *wdt) | |
62 | { | |
63 | u32 v = readl(wdt->regs + WDTCON_REG); | |
64 | ||
65 | return (v >> WDTCON_RMCS_SHIFT) & WDTCON_RMCS_MASK; | |
66 | } | |
67 | ||
68 | static int pic32_wdt_bootstatus(struct pic32_wdt *wdt) | |
69 | { | |
70 | u32 v = readl(wdt->rst_base); | |
71 | ||
72 | writel(RESETCON_WDT_TIMEOUT, PIC32_CLR(wdt->rst_base)); | |
73 | ||
74 | return v & RESETCON_WDT_TIMEOUT; | |
75 | } | |
76 | ||
77 | static u32 pic32_wdt_get_timeout_secs(struct pic32_wdt *wdt, struct device *dev) | |
78 | { | |
79 | unsigned long rate; | |
80 | u32 period, ps, terminal; | |
81 | ||
82 | rate = clk_get_rate(wdt->clk); | |
83 | ||
84 | dev_dbg(dev, "wdt: clk_id %d, clk_rate %lu (prescale)\n", | |
85 | pic32_wdt_get_clk_id(wdt), rate); | |
86 | ||
87 | /* default, prescaler of 32 (i.e. div-by-32) is implicit. */ | |
88 | rate >>= 5; | |
89 | if (!rate) | |
90 | return 0; | |
91 | ||
92 | /* calculate terminal count from postscaler. */ | |
93 | ps = pic32_wdt_get_post_scaler(wdt); | |
94 | terminal = BIT(ps); | |
95 | ||
96 | /* find time taken (in secs) to reach terminal count */ | |
97 | period = terminal / rate; | |
98 | dev_dbg(dev, | |
99 | "wdt: clk_rate %lu (postscale) / terminal %d, timeout %dsec\n", | |
100 | rate, terminal, period); | |
101 | ||
102 | return period; | |
103 | } | |
104 | ||
105 | static void pic32_wdt_keepalive(struct pic32_wdt *wdt) | |
106 | { | |
107 | /* write key through single half-word */ | |
108 | writew(WDTCON_CLR_KEY, wdt->regs + WDTCON_REG + 2); | |
109 | } | |
110 | ||
111 | static int pic32_wdt_start(struct watchdog_device *wdd) | |
112 | { | |
113 | struct pic32_wdt *wdt = watchdog_get_drvdata(wdd); | |
114 | ||
115 | writel(WDTCON_ON, PIC32_SET(wdt->regs + WDTCON_REG)); | |
116 | pic32_wdt_keepalive(wdt); | |
117 | ||
118 | return 0; | |
119 | } | |
120 | ||
121 | static int pic32_wdt_stop(struct watchdog_device *wdd) | |
122 | { | |
123 | struct pic32_wdt *wdt = watchdog_get_drvdata(wdd); | |
124 | ||
125 | writel(WDTCON_ON, PIC32_CLR(wdt->regs + WDTCON_REG)); | |
126 | ||
127 | /* | |
128 | * Cannot touch registers in the CPU cycle following clearing the | |
129 | * ON bit. | |
130 | */ | |
131 | nop(); | |
132 | ||
133 | return 0; | |
134 | } | |
135 | ||
136 | static int pic32_wdt_ping(struct watchdog_device *wdd) | |
137 | { | |
138 | struct pic32_wdt *wdt = watchdog_get_drvdata(wdd); | |
139 | ||
140 | pic32_wdt_keepalive(wdt); | |
141 | ||
142 | return 0; | |
143 | } | |
144 | ||
145 | static const struct watchdog_ops pic32_wdt_fops = { | |
146 | .owner = THIS_MODULE, | |
147 | .start = pic32_wdt_start, | |
148 | .stop = pic32_wdt_stop, | |
149 | .ping = pic32_wdt_ping, | |
150 | }; | |
151 | ||
152 | static const struct watchdog_info pic32_wdt_ident = { | |
153 | .options = WDIOF_KEEPALIVEPING | | |
154 | WDIOF_MAGICCLOSE | WDIOF_CARDRESET, | |
155 | .identity = "PIC32 Watchdog", | |
156 | }; | |
157 | ||
158 | static struct watchdog_device pic32_wdd = { | |
159 | .info = &pic32_wdt_ident, | |
160 | .ops = &pic32_wdt_fops, | |
161 | }; | |
162 | ||
163 | static const struct of_device_id pic32_wdt_dt_ids[] = { | |
164 | { .compatible = "microchip,pic32mzda-wdt", }, | |
165 | { /* sentinel */ } | |
166 | }; | |
167 | MODULE_DEVICE_TABLE(of, pic32_wdt_dt_ids); | |
168 | ||
169 | static int pic32_wdt_drv_probe(struct platform_device *pdev) | |
170 | { | |
171 | int ret; | |
172 | struct watchdog_device *wdd = &pic32_wdd; | |
173 | struct pic32_wdt *wdt; | |
174 | struct resource *mem; | |
175 | ||
176 | wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); | |
db6d2d0e WY |
177 | if (!wdt) |
178 | return -ENOMEM; | |
8f91fc56 JH |
179 | |
180 | mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
181 | wdt->regs = devm_ioremap_resource(&pdev->dev, mem); | |
182 | if (IS_ERR(wdt->regs)) | |
183 | return PTR_ERR(wdt->regs); | |
184 | ||
185 | wdt->rst_base = devm_ioremap(&pdev->dev, PIC32_BASE_RESET, 0x10); | |
cddd74db WY |
186 | if (!wdt->rst_base) |
187 | return -ENOMEM; | |
8f91fc56 JH |
188 | |
189 | wdt->clk = devm_clk_get(&pdev->dev, NULL); | |
190 | if (IS_ERR(wdt->clk)) { | |
191 | dev_err(&pdev->dev, "clk not found\n"); | |
192 | return PTR_ERR(wdt->clk); | |
193 | } | |
194 | ||
195 | ret = clk_prepare_enable(wdt->clk); | |
196 | if (ret) { | |
197 | dev_err(&pdev->dev, "clk enable failed\n"); | |
198 | return ret; | |
199 | } | |
200 | ||
201 | if (pic32_wdt_is_win_enabled(wdt)) { | |
202 | dev_err(&pdev->dev, "windowed-clear mode is not supported.\n"); | |
203 | ret = -ENODEV; | |
204 | goto out_disable_clk; | |
205 | } | |
206 | ||
207 | wdd->timeout = pic32_wdt_get_timeout_secs(wdt, &pdev->dev); | |
208 | if (!wdd->timeout) { | |
209 | dev_err(&pdev->dev, | |
210 | "failed to read watchdog register timeout\n"); | |
211 | ret = -EINVAL; | |
212 | goto out_disable_clk; | |
213 | } | |
214 | ||
215 | dev_info(&pdev->dev, "timeout %d\n", wdd->timeout); | |
216 | ||
217 | wdd->bootstatus = pic32_wdt_bootstatus(wdt) ? WDIOF_CARDRESET : 0; | |
218 | ||
219 | watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT); | |
220 | watchdog_set_drvdata(wdd, wdt); | |
221 | ||
222 | ret = watchdog_register_device(wdd); | |
223 | if (ret) { | |
224 | dev_err(&pdev->dev, "watchdog register failed, err %d\n", ret); | |
225 | goto out_disable_clk; | |
226 | } | |
227 | ||
228 | platform_set_drvdata(pdev, wdd); | |
229 | ||
230 | return 0; | |
231 | ||
232 | out_disable_clk: | |
233 | clk_disable_unprepare(wdt->clk); | |
234 | ||
235 | return ret; | |
236 | } | |
237 | ||
238 | static int pic32_wdt_drv_remove(struct platform_device *pdev) | |
239 | { | |
240 | struct watchdog_device *wdd = platform_get_drvdata(pdev); | |
241 | struct pic32_wdt *wdt = watchdog_get_drvdata(wdd); | |
242 | ||
243 | watchdog_unregister_device(wdd); | |
244 | clk_disable_unprepare(wdt->clk); | |
245 | ||
246 | return 0; | |
247 | } | |
248 | ||
249 | static struct platform_driver pic32_wdt_driver = { | |
250 | .probe = pic32_wdt_drv_probe, | |
251 | .remove = pic32_wdt_drv_remove, | |
252 | .driver = { | |
253 | .name = "pic32-wdt", | |
8f91fc56 JH |
254 | .of_match_table = of_match_ptr(pic32_wdt_dt_ids), |
255 | } | |
256 | }; | |
257 | ||
258 | module_platform_driver(pic32_wdt_driver); | |
259 | ||
260 | MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>"); | |
261 | MODULE_DESCRIPTION("Microchip PIC32 Watchdog Timer"); | |
262 | MODULE_LICENSE("GPL"); |