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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * PIC32 deadman timer driver
4 *
5 * Purna Chandra Mandal <purna.mandal@microchip.com>
6 * Copyright (c) 2016, Microchip Technology Inc.
7 */
8#include <linux/clk.h>
9#include <linux/device.h>
10#include <linux/err.h>
11#include <linux/io.h>
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/of.h>
15#include <linux/of_device.h>
16#include <linux/platform_device.h>
17#include <linux/pm.h>
18#include <linux/watchdog.h>
19
20#include <asm/mach-pic32/pic32.h>
21
22/* Deadman Timer Regs */
23#define DMTCON_REG 0x00
24#define DMTPRECLR_REG 0x10
25#define DMTCLR_REG 0x20
26#define DMTSTAT_REG 0x30
27#define DMTCNT_REG 0x40
28#define DMTPSCNT_REG 0x60
29#define DMTPSINTV_REG 0x70
30
31/* Deadman Timer Regs fields */
32#define DMT_ON BIT(15)
33#define DMT_STEP1_KEY BIT(6)
34#define DMT_STEP2_KEY BIT(3)
35#define DMTSTAT_WINOPN BIT(0)
36#define DMTSTAT_EVENT BIT(5)
37#define DMTSTAT_BAD2 BIT(6)
38#define DMTSTAT_BAD1 BIT(7)
39
40/* Reset Control Register fields for watchdog */
41#define RESETCON_DMT_TIMEOUT BIT(5)
42
43struct pic32_dmt {
44 void __iomem *regs;
45 struct clk *clk;
46};
47
48static inline void dmt_enable(struct pic32_dmt *dmt)
49{
50 writel(DMT_ON, PIC32_SET(dmt->regs + DMTCON_REG));
51}
52
53static inline void dmt_disable(struct pic32_dmt *dmt)
54{
55 writel(DMT_ON, PIC32_CLR(dmt->regs + DMTCON_REG));
56 /*
57 * Cannot touch registers in the CPU cycle following clearing the
58 * ON bit.
59 */
60 nop();
61}
62
63static inline int dmt_bad_status(struct pic32_dmt *dmt)
64{
65 u32 val;
66
67 val = readl(dmt->regs + DMTSTAT_REG);
68 val &= (DMTSTAT_BAD1 | DMTSTAT_BAD2 | DMTSTAT_EVENT);
69 if (val)
70 return -EAGAIN;
71
72 return 0;
73}
74
75static inline int dmt_keepalive(struct pic32_dmt *dmt)
76{
77 u32 v;
78 u32 timeout = 500;
79
80 /* set pre-clear key */
81 writel(DMT_STEP1_KEY << 8, dmt->regs + DMTPRECLR_REG);
82
83 /* wait for DMT window to open */
84 while (--timeout) {
85 v = readl(dmt->regs + DMTSTAT_REG) & DMTSTAT_WINOPN;
86 if (v == DMTSTAT_WINOPN)
87 break;
88 }
89
90 /* apply key2 */
91 writel(DMT_STEP2_KEY, dmt->regs + DMTCLR_REG);
92
93 /* check whether keys are latched correctly */
94 return dmt_bad_status(dmt);
95}
96
97static inline u32 pic32_dmt_get_timeout_secs(struct pic32_dmt *dmt)
98{
99 unsigned long rate;
100
101 rate = clk_get_rate(dmt->clk);
102 if (rate)
103 return readl(dmt->regs + DMTPSCNT_REG) / rate;
104
105 return 0;
106}
107
108static inline u32 pic32_dmt_bootstatus(struct pic32_dmt *dmt)
109{
110 u32 v;
111 void __iomem *rst_base;
112
113 rst_base = ioremap(PIC32_BASE_RESET, 0x10);
114 if (!rst_base)
115 return 0;
116
117 v = readl(rst_base);
118
119 writel(RESETCON_DMT_TIMEOUT, PIC32_CLR(rst_base));
120
121 iounmap(rst_base);
122 return v & RESETCON_DMT_TIMEOUT;
123}
124
125static int pic32_dmt_start(struct watchdog_device *wdd)
126{
127 struct pic32_dmt *dmt = watchdog_get_drvdata(wdd);
128
129 dmt_enable(dmt);
130 return dmt_keepalive(dmt);
131}
132
133static int pic32_dmt_stop(struct watchdog_device *wdd)
134{
135 struct pic32_dmt *dmt = watchdog_get_drvdata(wdd);
136
137 dmt_disable(dmt);
138
139 return 0;
140}
141
142static int pic32_dmt_ping(struct watchdog_device *wdd)
143{
144 struct pic32_dmt *dmt = watchdog_get_drvdata(wdd);
145
146 return dmt_keepalive(dmt);
147}
148
149static const struct watchdog_ops pic32_dmt_fops = {
150 .owner = THIS_MODULE,
151 .start = pic32_dmt_start,
152 .stop = pic32_dmt_stop,
153 .ping = pic32_dmt_ping,
154};
155
156static const struct watchdog_info pic32_dmt_ident = {
157 .options = WDIOF_KEEPALIVEPING |
158 WDIOF_MAGICCLOSE,
159 .identity = "PIC32 Deadman Timer",
160};
161
162static struct watchdog_device pic32_dmt_wdd = {
163 .info = &pic32_dmt_ident,
164 .ops = &pic32_dmt_fops,
165};
166
167static void pic32_clk_disable_unprepare(void *data)
168{
169 clk_disable_unprepare(data);
170}
171
172static int pic32_dmt_probe(struct platform_device *pdev)
173{
174 struct device *dev = &pdev->dev;
175 int ret;
176 struct pic32_dmt *dmt;
177 struct watchdog_device *wdd = &pic32_dmt_wdd;
178
179 dmt = devm_kzalloc(dev, sizeof(*dmt), GFP_KERNEL);
180 if (!dmt)
181 return -ENOMEM;
182
183 dmt->regs = devm_platform_ioremap_resource(pdev, 0);
184 if (IS_ERR(dmt->regs))
185 return PTR_ERR(dmt->regs);
186
187 dmt->clk = devm_clk_get(dev, NULL);
188 if (IS_ERR(dmt->clk)) {
189 dev_err(dev, "clk not found\n");
190 return PTR_ERR(dmt->clk);
191 }
192
193 ret = clk_prepare_enable(dmt->clk);
194 if (ret)
195 return ret;
196 ret = devm_add_action_or_reset(dev, pic32_clk_disable_unprepare,
197 dmt->clk);
198 if (ret)
199 return ret;
200
201 wdd->timeout = pic32_dmt_get_timeout_secs(dmt);
202 if (!wdd->timeout) {
203 dev_err(dev, "failed to read watchdog register timeout\n");
204 return -EINVAL;
205 }
206
207 dev_info(dev, "timeout %d\n", wdd->timeout);
208
209 wdd->bootstatus = pic32_dmt_bootstatus(dmt) ? WDIOF_CARDRESET : 0;
210
211 watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT);
212 watchdog_set_drvdata(wdd, dmt);
213
214 ret = devm_watchdog_register_device(dev, wdd);
215 if (ret)
216 return ret;
217
218 platform_set_drvdata(pdev, wdd);
219 return 0;
220}
221
222static const struct of_device_id pic32_dmt_of_ids[] = {
223 { .compatible = "microchip,pic32mzda-dmt",},
224 { /* sentinel */ }
225};
226MODULE_DEVICE_TABLE(of, pic32_dmt_of_ids);
227
228static struct platform_driver pic32_dmt_driver = {
229 .probe = pic32_dmt_probe,
230 .driver = {
231 .name = "pic32-dmt",
232 .of_match_table = of_match_ptr(pic32_dmt_of_ids),
233 }
234};
235
236module_platform_driver(pic32_dmt_driver);
237
238MODULE_AUTHOR("Purna Chandra Mandal <purna.mandal@microchip.com>");
239MODULE_DESCRIPTION("Microchip PIC32 DMT Driver");
240MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * PIC32 deadman timer driver
4 *
5 * Purna Chandra Mandal <purna.mandal@microchip.com>
6 * Copyright (c) 2016, Microchip Technology Inc.
7 */
8#include <linux/clk.h>
9#include <linux/device.h>
10#include <linux/err.h>
11#include <linux/io.h>
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/of.h>
15#include <linux/of_device.h>
16#include <linux/platform_device.h>
17#include <linux/pm.h>
18#include <linux/watchdog.h>
19
20#include <asm/mach-pic32/pic32.h>
21
22/* Deadman Timer Regs */
23#define DMTCON_REG 0x00
24#define DMTPRECLR_REG 0x10
25#define DMTCLR_REG 0x20
26#define DMTSTAT_REG 0x30
27#define DMTCNT_REG 0x40
28#define DMTPSCNT_REG 0x60
29#define DMTPSINTV_REG 0x70
30
31/* Deadman Timer Regs fields */
32#define DMT_ON BIT(15)
33#define DMT_STEP1_KEY BIT(6)
34#define DMT_STEP2_KEY BIT(3)
35#define DMTSTAT_WINOPN BIT(0)
36#define DMTSTAT_EVENT BIT(5)
37#define DMTSTAT_BAD2 BIT(6)
38#define DMTSTAT_BAD1 BIT(7)
39
40/* Reset Control Register fields for watchdog */
41#define RESETCON_DMT_TIMEOUT BIT(5)
42
43struct pic32_dmt {
44 void __iomem *regs;
45 struct clk *clk;
46};
47
48static inline void dmt_enable(struct pic32_dmt *dmt)
49{
50 writel(DMT_ON, PIC32_SET(dmt->regs + DMTCON_REG));
51}
52
53static inline void dmt_disable(struct pic32_dmt *dmt)
54{
55 writel(DMT_ON, PIC32_CLR(dmt->regs + DMTCON_REG));
56 /*
57 * Cannot touch registers in the CPU cycle following clearing the
58 * ON bit.
59 */
60 nop();
61}
62
63static inline int dmt_bad_status(struct pic32_dmt *dmt)
64{
65 u32 val;
66
67 val = readl(dmt->regs + DMTSTAT_REG);
68 val &= (DMTSTAT_BAD1 | DMTSTAT_BAD2 | DMTSTAT_EVENT);
69 if (val)
70 return -EAGAIN;
71
72 return 0;
73}
74
75static inline int dmt_keepalive(struct pic32_dmt *dmt)
76{
77 u32 v;
78 u32 timeout = 500;
79
80 /* set pre-clear key */
81 writel(DMT_STEP1_KEY << 8, dmt->regs + DMTPRECLR_REG);
82
83 /* wait for DMT window to open */
84 while (--timeout) {
85 v = readl(dmt->regs + DMTSTAT_REG) & DMTSTAT_WINOPN;
86 if (v == DMTSTAT_WINOPN)
87 break;
88 }
89
90 /* apply key2 */
91 writel(DMT_STEP2_KEY, dmt->regs + DMTCLR_REG);
92
93 /* check whether keys are latched correctly */
94 return dmt_bad_status(dmt);
95}
96
97static inline u32 pic32_dmt_get_timeout_secs(struct pic32_dmt *dmt)
98{
99 unsigned long rate;
100
101 rate = clk_get_rate(dmt->clk);
102 if (rate)
103 return readl(dmt->regs + DMTPSCNT_REG) / rate;
104
105 return 0;
106}
107
108static inline u32 pic32_dmt_bootstatus(struct pic32_dmt *dmt)
109{
110 u32 v;
111 void __iomem *rst_base;
112
113 rst_base = ioremap(PIC32_BASE_RESET, 0x10);
114 if (!rst_base)
115 return 0;
116
117 v = readl(rst_base);
118
119 writel(RESETCON_DMT_TIMEOUT, PIC32_CLR(rst_base));
120
121 iounmap(rst_base);
122 return v & RESETCON_DMT_TIMEOUT;
123}
124
125static int pic32_dmt_start(struct watchdog_device *wdd)
126{
127 struct pic32_dmt *dmt = watchdog_get_drvdata(wdd);
128
129 dmt_enable(dmt);
130 return dmt_keepalive(dmt);
131}
132
133static int pic32_dmt_stop(struct watchdog_device *wdd)
134{
135 struct pic32_dmt *dmt = watchdog_get_drvdata(wdd);
136
137 dmt_disable(dmt);
138
139 return 0;
140}
141
142static int pic32_dmt_ping(struct watchdog_device *wdd)
143{
144 struct pic32_dmt *dmt = watchdog_get_drvdata(wdd);
145
146 return dmt_keepalive(dmt);
147}
148
149static const struct watchdog_ops pic32_dmt_fops = {
150 .owner = THIS_MODULE,
151 .start = pic32_dmt_start,
152 .stop = pic32_dmt_stop,
153 .ping = pic32_dmt_ping,
154};
155
156static const struct watchdog_info pic32_dmt_ident = {
157 .options = WDIOF_KEEPALIVEPING |
158 WDIOF_MAGICCLOSE,
159 .identity = "PIC32 Deadman Timer",
160};
161
162static struct watchdog_device pic32_dmt_wdd = {
163 .info = &pic32_dmt_ident,
164 .ops = &pic32_dmt_fops,
165};
166
167static void pic32_clk_disable_unprepare(void *data)
168{
169 clk_disable_unprepare(data);
170}
171
172static int pic32_dmt_probe(struct platform_device *pdev)
173{
174 struct device *dev = &pdev->dev;
175 int ret;
176 struct pic32_dmt *dmt;
177 struct watchdog_device *wdd = &pic32_dmt_wdd;
178
179 dmt = devm_kzalloc(dev, sizeof(*dmt), GFP_KERNEL);
180 if (!dmt)
181 return -ENOMEM;
182
183 dmt->regs = devm_platform_ioremap_resource(pdev, 0);
184 if (IS_ERR(dmt->regs))
185 return PTR_ERR(dmt->regs);
186
187 dmt->clk = devm_clk_get(dev, NULL);
188 if (IS_ERR(dmt->clk)) {
189 dev_err(dev, "clk not found\n");
190 return PTR_ERR(dmt->clk);
191 }
192
193 ret = clk_prepare_enable(dmt->clk);
194 if (ret)
195 return ret;
196 ret = devm_add_action_or_reset(dev, pic32_clk_disable_unprepare,
197 dmt->clk);
198 if (ret)
199 return ret;
200
201 wdd->timeout = pic32_dmt_get_timeout_secs(dmt);
202 if (!wdd->timeout) {
203 dev_err(dev, "failed to read watchdog register timeout\n");
204 return -EINVAL;
205 }
206
207 dev_info(dev, "timeout %d\n", wdd->timeout);
208
209 wdd->bootstatus = pic32_dmt_bootstatus(dmt) ? WDIOF_CARDRESET : 0;
210
211 watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT);
212 watchdog_set_drvdata(wdd, dmt);
213
214 ret = devm_watchdog_register_device(dev, wdd);
215 if (ret)
216 return ret;
217
218 platform_set_drvdata(pdev, wdd);
219 return 0;
220}
221
222static const struct of_device_id pic32_dmt_of_ids[] = {
223 { .compatible = "microchip,pic32mzda-dmt",},
224 { /* sentinel */ }
225};
226MODULE_DEVICE_TABLE(of, pic32_dmt_of_ids);
227
228static struct platform_driver pic32_dmt_driver = {
229 .probe = pic32_dmt_probe,
230 .driver = {
231 .name = "pic32-dmt",
232 .of_match_table = of_match_ptr(pic32_dmt_of_ids),
233 }
234};
235
236module_platform_driver(pic32_dmt_driver);
237
238MODULE_AUTHOR("Purna Chandra Mandal <purna.mandal@microchip.com>");
239MODULE_DESCRIPTION("Microchip PIC32 DMT Driver");
240MODULE_LICENSE("GPL");