On 02/01/2016 04:02 PM, Joshua Henderson wrote:
When enabled, the watchdog peripheral can be used to reset the device if the
WDT is not cleared periodically in software.
Commit description is a bit long.
Signed-off-by: Joshua Henderson <joshua.henderson@xxxxxxxxxxxxx>
Signed-off-by: Purna Chandra Mandal <purna.mandal@xxxxxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: <linux-mips@xxxxxxxxxxxxxx>
---
Note: Please merge this patch series through the MIPS tree.
---
drivers/watchdog/Kconfig | 14 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/pic32-wdt.c | 301 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 316 insertions(+)
create mode 100644 drivers/watchdog/pic32-wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 4f0e7be..131abc2 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1410,6 +1410,20 @@ config MT7621_WDT
help
Hardware driver for the Mediatek/Ralink MT7621/8 SoC Watchdog Timer.
+config PIC32_WDT
+ tristate "Microchip PIC32 hardware watchdog"
+ select WATCHDOG_CORE
+ depends on MACH_PIC32
+ default y
Sure you want "y" here ?
+ help
+ Watchdog driver for the built in watchdog hardware in a PIC32.
+
+ Configuration bits must be set appropriately for the watchdog to be
+ controlled by this driver.
+
+ To compile this driver as a loadable module, choose M here.
+ The module will be called pic32-wdt.
+
# PARISC Architecture
# POWERPC Architecture
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index f566753..244ed80 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -153,6 +153,7 @@ obj-$(CONFIG_LANTIQ_WDT) += lantiq_wdt.o
obj-$(CONFIG_RALINK_WDT) += rt2880_wdt.o
obj-$(CONFIG_IMGPDC_WDT) += imgpdc_wdt.o
obj-$(CONFIG_MT7621_WDT) += mt7621_wdt.o
+obj-$(CONFIG_PIC32_WDT) += pic32-wdt.o
# PARISC Architecture
diff --git a/drivers/watchdog/pic32-wdt.c b/drivers/watchdog/pic32-wdt.c
new file mode 100644
index 0000000..d80e62d
--- /dev/null
+++ b/drivers/watchdog/pic32-wdt.c
@@ -0,0 +1,301 @@
+/*
+ * PIC32 watchdog driver
+ *
+ * Joshua Henderson <joshua.henderson@xxxxxxxxxxxxx>
+ * Copyright (c) 2016, Microchip Technology Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/pm.h>
+#include <linux/watchdog.h>
+#include <linux/spinlock.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
Alphabetic order, please.
+
+#include <asm/mach-pic32/pic32.h>
+
+/* Watchdog Timer Registers */
+#define WDTCON_REG 0x00
+
+/* Watchdog Timer Control Register fields */
+#define WDTCON_WIN_EN 0x0001
+#define WDTCON_RMCS_MASK 0x0003
+#define WDTCON_RMCS_SHIFT 0x0006
+#define WDTCON_RMPS_MASK 0x001F
+#define WDTCON_RMPS_SHIFT 0x0008
+#define WDTCON_ON 0x8000
+#define WDTCON_CLR_KEY 0x5743
+
+/* Reset Control Register fields for watchdog */
+#define RESETCON_TIMEOUT_IDLE 0x0004
+#define RESETCON_TIMEOUT_SLEEP 0x0008
+#define RESETCON_WDT_TIMEOUT 0x0010
+
Can you use BIT() to make it easier to understand which values are bit masks ?
+struct pic32_wdt {
+ spinlock_t lock;
+ void __iomem *regs;
+ void __iomem *rst_base;
+ struct clk *clk;
+ unsigned long next_heartbeat;
+ unsigned long timeout;
+};
+
+static inline int wdt_is_enabled(struct pic32_wdt *wdt)
+{
+ return readl(wdt->regs + WDTCON_REG) & WDTCON_ON;
+}
Return bool.
+
+static inline int wdt_is_win_enabled(struct pic32_wdt *wdt)
+{
Return bool.
+ u32 v;
+
+ v = readl(wdt->regs + WDTCON_REG);
+ v &= WDTCON_WIN_EN;
+
+ return v;
return readl(wdt->regs + WDTCON_REG) & WDTCON_WIN_EN;
would be good enough and be more consistent with the other
function above.
+}
+
+static inline void wdt_enable(struct pic32_wdt *wdt)
+{
+ writel(WDTCON_ON, PIC32_SET(wdt->regs + WDTCON_REG));
+}
+
Can you use consistent function name prefixes ?
+static inline void wdt_disable(struct pic32_wdt *wdt)
+{
+ writel(WDTCON_ON, PIC32_CLR(wdt->regs + WDTCON_REG));
+ cpu_relax();
Is this needed ?
+}
+
+static inline u32 wdt_get_post_scaler(struct pic32_wdt *wdt)
+{
+ u32 v = readl(wdt->regs + WDTCON_REG);
+
+ return (v >> WDTCON_RMPS_SHIFT) & WDTCON_RMPS_MASK;
+}
+
+static inline u32 wdt_get_clk_id(struct pic32_wdt *wdt)
+{
+ u32 v = readl(wdt->regs + WDTCON_REG);
+
+ return (v >> WDTCON_RMCS_SHIFT) & WDTCON_RMCS_MASK;
+}
+
+static inline void wdt_keepalive(struct pic32_wdt *wdt)
+{
+ /* write key through single half-word */
+ writew(WDTCON_CLR_KEY, wdt->regs + WDTCON_REG + 2);
+}
+
+static int pic32_wdt_bootstatus(struct pic32_wdt *wdt)
+{
+ u32 v = readl(wdt->rst_base);
+
+ writel(RESETCON_WDT_TIMEOUT, PIC32_CLR(wdt->rst_base));
+
+ return v & RESETCON_WDT_TIMEOUT;
+}
+
+static int pic32_wdt_get_timeout_secs(struct pic32_wdt *wdt)
+{
+ unsigned long rate;
+ u32 period, ps, terminal;
+
+ rate = clk_get_rate(wdt->clk);
+ pr_debug("wdt: clk_id %d, clk_rate %lu (prescale)\n",
+ wdt_get_clk_id(wdt), rate);
+
+ /* default, prescaler of 32 (i.e. div-by-32) is implicit. */
+ rate >>= 5;
+
+ /* calculate terminal count from postscaler. */
+ ps = wdt_get_post_scaler(wdt);
+ terminal = 1 << ps;
BIT(ps) would be a bit nicer.
+
+ /* find time taken (in secs) to reach terminal count */
+ period = terminal / rate;
Can rate be 0 ?
+ pr_info("wdt: clk_rate %lu (postscale) / terminal %d, timeout %dsec\n",
+ rate, terminal, period);
Is this needed ? Seems like a debug message to me.
Users won't be able to make sense of it.
+
+ return period;
+}
+
+static void pic32_wdt_keepalive(struct pic32_wdt *wdt)
+{
+ wdt->next_heartbeat = jiffies +
+ msecs_to_jiffies(wdt->timeout * MSEC_PER_SEC);
+ wdt_keepalive(wdt);
+}
+
+static int pic32_wdt_start(struct watchdog_device *wdd)
+{
+ struct pic32_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ spin_lock(&wdt->lock);
Is this lock (on top of the lock provided by the watchdog subsystem)
needed ? If so, please explain.
+ if (wdt_is_enabled(wdt))
+ goto done;
Can this happpen, and if so, does it matter ?
+
+ wdt_enable(wdt);
+done:
+ pic32_wdt_keepalive(wdt);
+ spin_unlock(&wdt->lock);
+
+ return 0;
+}
+
+static int pic32_wdt_stop(struct watchdog_device *wdd)
+{
+ struct pic32_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ spin_lock(&wdt->lock);
+ wdt_disable(wdt);
+ spin_unlock(&wdt->lock);
+
+ return 0;
+}
+
+static int pic32_wdt_ping(struct watchdog_device *wdd)
+{
+ struct pic32_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ spin_lock(&wdt->lock);
+ pic32_wdt_keepalive(wdt);
+ spin_unlock(&wdt->lock);
+
+ return 0;
+}
+
+static unsigned int pic32_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+ struct pic32_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ return jiffies_to_msecs(wdt->next_heartbeat - jiffies) / MSEC_PER_SEC;
+}
Please no software "get_timeleft" implementation. If this is desired,
we can implement it in the watchdog core.
+
+static const struct watchdog_ops pic32_wdt_fops = {
+ .owner = THIS_MODULE,
+ .start = pic32_wdt_start,
+ .stop = pic32_wdt_stop,
+ .get_timeleft = pic32_wdt_get_timeleft,
+ .ping = pic32_wdt_ping,
+};
+
+static const struct watchdog_info pic32_wdt_ident = {
+ .options = WDIOF_KEEPALIVEPING |
+ WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
Is the timeout truly not configurable ?
+ .identity = "PIC32 Watchdog",
+};
+
+static struct watchdog_device pic32_wdd = {
+ .info = &pic32_wdt_ident,
+ .ops = &pic32_wdt_fops,
+ .min_timeout = 1,
+ .max_timeout = 1048,
Real or arbitrary ?
+};
+
+static const struct of_device_id pic32_wdt_dt_ids[] = {
+ { .compatible = "microchip,pic32mzda-wdt-v2", },
Is this compatible statement documented ?
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pic32_wdt_dt_ids);
+
+static int pic32_wdt_drv_probe(struct platform_device *pdev)
+{
+ int ret;
+ struct watchdog_device *wdd = &pic32_wdd;
+ struct pic32_wdt *wdt;
+ struct resource *mem;
+
+ wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+ if (IS_ERR(wdt))
+ return PTR_ERR(wdt);
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ wdt->regs = devm_ioremap_resource(&pdev->dev, mem);
+ if (IS_ERR(wdt->regs))
+ return PTR_ERR(wdt->regs);
+
+ wdt->rst_base = devm_ioremap(&pdev->dev, PIC32_BASE_RESET, 0x10);
+ if (IS_ERR(wdt->rst_base))
+ return PTR_ERR(wdt->rst_base);
+
+ wdt->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(wdt->clk)) {
+ dev_err(&pdev->dev, "clk not found\n");
+ return PTR_ERR(wdt->clk);
+ }
+
+ ret = clk_prepare_enable(wdt->clk);
+ if (ret) {
+ dev_err(&pdev->dev, "clk enable failed\n");
+ return ret;
+ }
+
+ if (wdt_is_win_enabled(wdt)) {
+ dev_err(&pdev->dev, "windowed-clear mode is not supported.\n");
+ ret = -EOPNOTSUPP;
+ goto out_disable_clk;
It might make more sense to check this first, before enabling the clock.
Also, can this not be disabled in software ?
+ }
+
+ wdt->timeout = pic32_wdt_get_timeout_secs(wdt);
Can timeout end up being 0 (less than 1 second) ?
+ spin_lock_init(&wdt->lock);
+
+ wdd->timeout = wdt->timeout;
wdt->timeout is only used to calculate next_timeout which is only used
to calculate the time left in software, which you should not do. Please drop.
+ wdd->bootstatus = pic32_wdt_bootstatus(wdt) ? WDIOF_CARDRESET : 0;
+
+ ret = watchdog_register_device(wdd);
+ if (ret) {
+ dev_err(&pdev->dev, "watchdog register failed, err %d\n", ret);
+ goto out_disable_clk;
+ }
+
+ watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT);
+ watchdog_set_drvdata(wdd, wdt);
Race condition.
+
+ platform_set_drvdata(pdev, wdd);
+ return 0;
+
+out_disable_clk:
+ clk_disable_unprepare(wdt->clk);
+
+ return ret;
+}
+
+static int pic32_wdt_drv_remove(struct platform_device *pdev)
+{
+ struct watchdog_device *wdd = platform_get_drvdata(pdev);
+ struct pic32_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ clk_disable_unprepare(wdt->clk);
+ watchdog_unregister_device(wdd);
Please call unregister first.
+
+ return 0;
+}
+
+static struct platform_driver pic32_wdt_driver = {
+ .probe = pic32_wdt_drv_probe,
+ .remove = pic32_wdt_drv_remove,
+ .driver = {
+ .name = "pi32-wdt",
pi32 or pic32 ?
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(pic32_wdt_dt_ids),
+ }
+};
+
+module_platform_driver(pic32_wdt_driver);
+
+MODULE_AUTHOR("Joshua Henderson <joshua.henderson@xxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Microchip PIC32 Watchdog Timer");
+MODULE_LICENSE("GPL");
--
1.7.9.5
