1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2022 Hewlett-Packard Enterprise Development Company, L.P. */
3
4 #include <linux/delay.h>
5 #include <linux/io.h>
6 #include <linux/module.h>
7 #include <linux/platform_device.h>
8 #include <linux/types.h>
9 #include <linux/watchdog.h>
10
11 #define MASK_WDGCS_ENABLE 0x01
12 #define MASK_WDGCS_RELOAD 0x04
13 #define MASK_WDGCS_NMIEN 0x08
14 #define MASK_WDGCS_WARN 0x80
15
16 #define WDT_MAX_TIMEOUT_MS 655350
17 #define WDT_DEFAULT_TIMEOUT 30
18 #define SECS_TO_WDOG_TICKS(x) ((x) * 100)
19 #define WDOG_TICKS_TO_SECS(x) ((x) / 100)
20
21 #define GXP_WDT_CNT_OFS 0x10
22 #define GXP_WDT_CTRL_OFS 0x16
23
24 struct gxp_wdt {
25 void __iomem *base;
26 struct watchdog_device wdd;
27 };
28
gxp_wdt_enable_reload(struct gxp_wdt * drvdata)29 static void gxp_wdt_enable_reload(struct gxp_wdt *drvdata)
30 {
31 u8 val;
32
33 val = readb(drvdata->base + GXP_WDT_CTRL_OFS);
34 val |= (MASK_WDGCS_ENABLE | MASK_WDGCS_RELOAD);
35 writeb(val, drvdata->base + GXP_WDT_CTRL_OFS);
36 }
37
gxp_wdt_start(struct watchdog_device * wdd)38 static int gxp_wdt_start(struct watchdog_device *wdd)
39 {
40 struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
41
42 writew(SECS_TO_WDOG_TICKS(wdd->timeout), drvdata->base + GXP_WDT_CNT_OFS);
43 gxp_wdt_enable_reload(drvdata);
44 return 0;
45 }
46
gxp_wdt_stop(struct watchdog_device * wdd)47 static int gxp_wdt_stop(struct watchdog_device *wdd)
48 {
49 struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
50 u8 val;
51
52 val = readb_relaxed(drvdata->base + GXP_WDT_CTRL_OFS);
53 val &= ~MASK_WDGCS_ENABLE;
54 writeb(val, drvdata->base + GXP_WDT_CTRL_OFS);
55 return 0;
56 }
57
gxp_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)58 static int gxp_wdt_set_timeout(struct watchdog_device *wdd,
59 unsigned int timeout)
60 {
61 struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
62 u32 actual;
63
64 wdd->timeout = timeout;
65 actual = min(timeout * 100, wdd->max_hw_heartbeat_ms / 10);
66 writew(actual, drvdata->base + GXP_WDT_CNT_OFS);
67
68 return 0;
69 }
70
gxp_wdt_get_timeleft(struct watchdog_device * wdd)71 static unsigned int gxp_wdt_get_timeleft(struct watchdog_device *wdd)
72 {
73 struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
74 u32 val = readw(drvdata->base + GXP_WDT_CNT_OFS);
75
76 return WDOG_TICKS_TO_SECS(val);
77 }
78
gxp_wdt_ping(struct watchdog_device * wdd)79 static int gxp_wdt_ping(struct watchdog_device *wdd)
80 {
81 struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
82
83 gxp_wdt_enable_reload(drvdata);
84 return 0;
85 }
86
gxp_restart(struct watchdog_device * wdd,unsigned long action,void * data)87 static int gxp_restart(struct watchdog_device *wdd, unsigned long action,
88 void *data)
89 {
90 struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
91
92 writew(1, drvdata->base + GXP_WDT_CNT_OFS);
93 gxp_wdt_enable_reload(drvdata);
94 mdelay(100);
95 return 0;
96 }
97
98 static const struct watchdog_ops gxp_wdt_ops = {
99 .owner = THIS_MODULE,
100 .start = gxp_wdt_start,
101 .stop = gxp_wdt_stop,
102 .ping = gxp_wdt_ping,
103 .set_timeout = gxp_wdt_set_timeout,
104 .get_timeleft = gxp_wdt_get_timeleft,
105 .restart = gxp_restart,
106 };
107
108 static const struct watchdog_info gxp_wdt_info = {
109 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
110 .identity = "HPE GXP Watchdog timer",
111 };
112
gxp_wdt_probe(struct platform_device * pdev)113 static int gxp_wdt_probe(struct platform_device *pdev)
114 {
115 struct device *dev = &pdev->dev;
116 struct gxp_wdt *drvdata;
117 int err;
118 u8 val;
119
120 drvdata = devm_kzalloc(dev, sizeof(struct gxp_wdt), GFP_KERNEL);
121 if (!drvdata)
122 return -ENOMEM;
123
124 /*
125 * The register area where the timer and watchdog reside is disarranged.
126 * Hence mapping individual register blocks for the timer and watchdog
127 * is not recommended as they would have access to each others
128 * registers. Based on feedback the watchdog is no longer part of the
129 * device tree file and the timer driver now creates the watchdog as a
130 * child device. During the watchdogs creation, the timer driver passes
131 * the base address to the watchdog over the private interface.
132 */
133
134 drvdata->base = (void __iomem *)dev->platform_data;
135
136 drvdata->wdd.info = &gxp_wdt_info;
137 drvdata->wdd.ops = &gxp_wdt_ops;
138 drvdata->wdd.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT_MS;
139 drvdata->wdd.parent = dev;
140 drvdata->wdd.timeout = WDT_DEFAULT_TIMEOUT;
141
142 watchdog_set_drvdata(&drvdata->wdd, drvdata);
143 watchdog_set_nowayout(&drvdata->wdd, WATCHDOG_NOWAYOUT);
144
145 val = readb(drvdata->base + GXP_WDT_CTRL_OFS);
146
147 if (val & MASK_WDGCS_ENABLE)
148 set_bit(WDOG_HW_RUNNING, &drvdata->wdd.status);
149
150 watchdog_set_restart_priority(&drvdata->wdd, 128);
151
152 watchdog_stop_on_reboot(&drvdata->wdd);
153 err = devm_watchdog_register_device(dev, &drvdata->wdd);
154 if (err)
155 return err;
156
157 dev_info(dev, "HPE GXP watchdog timer");
158
159 return 0;
160 }
161
162 static struct platform_driver gxp_wdt_driver = {
163 .probe = gxp_wdt_probe,
164 .driver = {
165 .name = "gxp-wdt",
166 },
167 };
168 module_platform_driver(gxp_wdt_driver);
169
170 MODULE_AUTHOR("Nick Hawkins <nick.hawkins@hpe.com>");
171 MODULE_AUTHOR("Jean-Marie Verdun <verdun@hpe.com>");
172 MODULE_DESCRIPTION("Driver for GXP watchdog timer");
173 MODULE_LICENSE("GPL");
174