Re: [PATCH v2 2/2] watchdog: Add Apple SoC watchdog driver

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 12/3/21 5:50 AM, Hector Martin wrote:
On 02/12/2021 23.36, Guenter Roeck wrote:
On 12/1/21 10:44 PM, Hector Martin "marcan" wrote:


On 2021年12月1日 1:18:09 JST, Sven Peter <sven@xxxxxxxxxxxxx> wrote:
Add support for the watchdog timer found in Apple SoCs. This driver is
also required to reboot these machines.

Signed-off-by: Sven Peter <sven@xxxxxxxxxxxxx>
---
v1 -> v2:
- set the default timeout to 30s and call watchdog_init_timeout
    to allow the device tree to override it
- set WDOG_HW_RUNNING if the watchdog is enabled at boot
- check that the clock rate is not zero
- use unsigned long instead of u32 for clk_rate
- use devm_add_action_or_reset instead of manually calling
    clk_disable_unprepare
- explain the magic number in apple_wdt_restart

MAINTAINERS                  |   1 +
drivers/watchdog/Kconfig     |  12 ++
drivers/watchdog/Makefile    |   1 +
drivers/watchdog/apple_wdt.c | 226 +++++++++++++++++++++++++++++++++++
4 files changed, 240 insertions(+)
create mode 100644 drivers/watchdog/apple_wdt.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 859201bbd4e8..6190f0b40983 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1757,6 +1757,7 @@ F:    drivers/i2c/busses/i2c-pasemi-platform.c
F:    drivers/irqchip/irq-apple-aic.c
F:    drivers/mailbox/apple-mailbox.c
F:    drivers/pinctrl/pinctrl-apple-gpio.c
+F:    drivers/watchdog/apple_wdt.c
F:    include/dt-bindings/interrupt-controller/apple-aic.h
F:    include/dt-bindings/pinctrl/apple.h
F:    include/linux/apple-mailbox.h
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 9d222ba17ec6..170dec880c8f 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -976,6 +976,18 @@ config MSC313E_WATCHDOG
      To compile this driver as a module, choose M here: the
      module will be called msc313e_wdt.

+config APPLE_WATCHDOG
+    tristate "Apple SoC watchdog"
+    depends on ARCH_APPLE || COMPILE_TEST
+    select WATCHDOG_CORE
+    help
+      Say Y here to include support for the Watchdog found in Apple
+      SoCs such as the M1. Next to the common watchdog features this
+      driver is also required in order to reboot these SoCs.
+
+      To compile this driver as a module, choose M here: the
+      module will be called apple_wdt.
+
# X86 (i386 + ia64 + x86_64) Architecture

config ACQUIRE_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 2ee97064145b..270a518bd8f3 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -93,6 +93,7 @@ obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o
obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o
obj-$(CONFIG_VISCONTI_WATCHDOG) += visconti_wdt.o
obj-$(CONFIG_MSC313E_WATCHDOG) += msc313e_wdt.o
+obj-$(CONFIG_APPLE_WATCHDOG) += apple_wdt.o

# X86 (i386 + ia64 + x86_64) Architecture
obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
diff --git a/drivers/watchdog/apple_wdt.c b/drivers/watchdog/apple_wdt.c
new file mode 100644
index 000000000000..76e5bedd50d1
--- /dev/null
+++ b/drivers/watchdog/apple_wdt.c
@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SoC Watchdog driver
+ *
+ * Copyright (C) The Asahi Linux Contributors
+ */
+
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/limits.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+/*
+ * Apple Watchdog MMIO registers
+ *
+ * This HW block has three separate watchdogs. WD0 resets the machine
+ * to recovery mode and is not very useful for us. WD1 and WD2 trigger a normal
+ * machine reset. WD0 additionally supports a configurable interrupt.
+ * This information can be used to implement pretimeout support at a later time.
+ *
+ * APPLE_WDT_WDx_CUR_TIME is a simple counter incremented for each tick of the
+ * reference clock. It can also be overwritten to any value.
+ * Whenever APPLE_WDT_CTRL_RESET_EN is set in APPLE_WDT_WDx_CTRL and
+ * APPLE_WDTx_WD1_CUR_TIME >= APPLE_WDTx_WD1_BITE_TIME the entire machine is
+ * reset.
+ * Whenever APPLE_WDT_CTRL_IRQ_EN is set and APPLE_WDTx_WD1_CUR_TIME >=
+ * APPLE_WDTx_WD1_BARK_TIME an interrupt is triggered and
+ * APPLE_WDT_CTRL_IRQ_STATUS is set. The interrupt can be cleared by writing
+ * 1 to APPLE_WDT_CTRL_IRQ_STATUS.
+ */
+#define APPLE_WDT_WD0_CUR_TIME        0x00
+#define APPLE_WDT_WD0_BITE_TIME        0x04
+#define APPLE_WDT_WD0_BARK_TIME        0x08
+#define APPLE_WDT_WD0_CTRL        0x0c
+
+#define APPLE_WDT_WD1_CUR_TIME        0x10
+#define APPLE_WDT_WD1_BITE_TIME        0x14
+#define APPLE_WDT_WD1_CTRL        0x1c
+
+#define APPLE_WDT_WD2_CUR_TIME        0x20
+#define APPLE_WDT_WD2_BITE_TIME        0x24
+#define APPLE_WDT_WD2_CTRL        0x2c
+
+#define APPLE_WDT_CTRL_IRQ_EN        BIT(0)
+#define APPLE_WDT_CTRL_IRQ_STATUS    BIT(1)
+#define APPLE_WDT_CTRL_RESET_EN        BIT(2)
+
+#define APPLE_WDT_TIMEOUT_DEFAULT    30
+
+struct apple_wdt {
+    struct watchdog_device wdd;
+    void __iomem *regs;
+    unsigned long clk_rate;
+};
+
+static struct apple_wdt *to_apple_wdt(struct watchdog_device *wdd)
+{
+    return container_of(wdd, struct apple_wdt, wdd);
+}
+
+static int apple_wdt_start(struct watchdog_device *wdd)
+{
+    struct apple_wdt *wdt = to_apple_wdt(wdd);
+
+    writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CUR_TIME);
+    writel_relaxed(APPLE_WDT_CTRL_RESET_EN, wdt->regs + APPLE_WDT_WD1_CTRL);
+
+    return 0;
+}
+
+static int apple_wdt_stop(struct watchdog_device *wdd)
+{
+    struct apple_wdt *wdt = to_apple_wdt(wdd);
+
+    writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CTRL);
+
+    return 0;
+}
+
+static int apple_wdt_ping(struct watchdog_device *wdd)
+{
+    struct apple_wdt *wdt = to_apple_wdt(wdd);
+
+    writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CUR_TIME);
+
+    return 0;
+}
+
+static int apple_wdt_set_timeout(struct watchdog_device *wdd, unsigned int s)
+{
+    struct apple_wdt *wdt = to_apple_wdt(wdd);
+
+    writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CUR_TIME);
+    writel_relaxed(wdt->clk_rate * s, wdt->regs + APPLE_WDT_WD1_BITE_TIME);
+
+    wdd->timeout = s;
+
+    return 0;
+}
+
+static unsigned int apple_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+    struct apple_wdt *wdt = to_apple_wdt(wdd);
+    u32 cur_time, reset_time;
+
+    cur_time = readl_relaxed(wdt->regs + APPLE_WDT_WD1_CUR_TIME);
+    reset_time = readl_relaxed(wdt->regs + APPLE_WDT_WD1_BITE_TIME);
+
+    return (reset_time - cur_time) / wdt->clk_rate;
+}
+
+static int apple_wdt_restart(struct watchdog_device *wdd, unsigned long mode,
+                 void *cmd)
+{
+    struct apple_wdt *wdt = to_apple_wdt(wdd);
+
+    writel_relaxed(APPLE_WDT_CTRL_RESET_EN, wdt->regs + APPLE_WDT_WD1_CTRL);
+    writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_BITE_TIME);
+    writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CUR_TIME);
+
+    /*
+     * Flush writes and then wait for the SoC to reset. Even though the
+     * reset is queued almost immediately experiments have shown that it
+     * can take up to ~20-25ms until the SoC is actually reset. Just wait
+     * 50ms here to be safe.
+     */
+    (void)readl_relaxed(wdt->regs + APPLE_WDT_WD1_CUR_TIME);
+    mdelay(50);
+
+    return 0;
+}
+
+static void apple_wdt_clk_disable_unprepare(void *data)
+{
+    clk_disable_unprepare(data);
+}
+
+static struct watchdog_ops apple_wdt_ops = {
+    .owner = THIS_MODULE,
+    .start = apple_wdt_start,
+    .stop = apple_wdt_stop,
+    .ping = apple_wdt_ping,
+    .set_timeout = apple_wdt_set_timeout,
+    .get_timeleft = apple_wdt_get_timeleft,
+    .restart = apple_wdt_restart,
+};
+
+static struct watchdog_info apple_wdt_info = {
+    .identity = "Apple SoC Watchdog",
+    .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+};
+
+static int apple_wdt_probe(struct platform_device *pdev)
+{
+    struct device *dev = &pdev->dev;
+    struct apple_wdt *wdt;
+    struct clk *clk;
+    u32 wdt_ctrl;
+    int ret;
+
+    wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+    if (!wdt)
+        return -ENOMEM;
+
+    wdt->regs = devm_platform_ioremap_resource(pdev, 0);
+    if (IS_ERR(wdt->regs))
+        return PTR_ERR(wdt->regs);
+
+    clk = devm_clk_get(dev, NULL);
+    if (IS_ERR(clk))
+        return PTR_ERR(clk);
+
+    ret = clk_prepare_enable(clk);
+    if (ret)
+        return ret;
+
+    ret = devm_add_action_or_reset(dev, apple_wdt_clk_disable_unprepare,
+                       clk);
+    if (ret)
+        return ret;
+
+    wdt->clk_rate = clk_get_rate(clk);
+    if (!wdt->clk_rate)
+        return -EINVAL;
+
+    wdt->wdd.ops = &apple_wdt_ops;
+    wdt->wdd.info = &apple_wdt_info;
+    wdt->wdd.max_timeout = U32_MAX / wdt->clk_rate;
+    wdt->wdd.timeout = APPLE_WDT_TIMEOUT_DEFAULT;
+
+    wdt_ctrl = readl_relaxed(wdt->regs + APPLE_WDT_WD1_CTRL);
+    if (wdt_ctrl & APPLE_WDT_CTRL_RESET_EN)
+        set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
+
+    watchdog_init_timeout(&wdt->wdd, 0, dev);
+    apple_wdt_set_timeout(&wdt->wdd, wdt->wdd.timeout);
+    watchdog_stop_on_unregister(&wdt->wdd);
+    watchdog_set_restart_priority(&wdt->wdd, 128);
+
+    return devm_watchdog_register_device(dev, &wdt->wdd);
+}
+
+static const struct of_device_id apple_wdt_of_match[] = {
+    { .compatible = "apple,wdt" },
+    {},
+};
+MODULE_DEVICE_TABLE(of, apple_wdt_of_match);
+
+static struct platform_driver apple_wdt_driver = {
+    .driver = {
+        .name = "apple-watchdog",
+        .of_match_table = apple_wdt_of_match,
+    },
+    .probe = apple_wdt_probe,
+};
+module_platform_driver(apple_wdt_driver);
+
+MODULE_DESCRIPTION("Apple SoC watchdog driver");
+MODULE_AUTHOR("Sven Peter <sven@xxxxxxxxxxxxx>");
+MODULE_LICENSE("Dual MIT/GPL");

Reviewed-by: Hector Martin <marcan@xxxxxxxxx>

Thanks, looks good! Any chance you can do a quick v3 with the MAINTAINERS changes split off? As usual, I'd rather make life easier for people merging upstream :)


Usually I don't ask for such a split, and I don't recall that being an issue.
So, from my perspective, that is not necessary.

We're upstreaming a bunch of things in parallel that touch the same MAINTAINERS section, and if each of those goes through subsystem trees, they all end up creating a pile of conflicts when merged. This has already happened a few times (I got a ping from linux-next about it the other day).

To make life easier for upstream mergers, we prefer to split off MAINTAINERS changes. Then instead of going through the subsystem tree, I can push those up through the SoC tree, making sure to resolve any conflicts/ordering issues. Then everyone upstream of us is happy :-)


Ok, makes sense.

Thanks,
Guenter



[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux