watchdog: stm32mp: Add watchdog driver

This patch adds IWDG (Independent WatchDoG) support for
STM32MP platform.

Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Stefan Roese <sr@denx.de>

diff --git a/MAINTAINERS b/MAINTAINERS
index 3662579..2e5a248 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -312,6 +312,7 @@ F:  drivers/ram/stm32mp1/
 F:     drivers/misc/stm32_rcc.c
 F:     drivers/reset/stm32-reset.c
 F:     drivers/spi/stm32_qspi.c
+F:     drivers/watchdog/stm32mp_wdt.c
 
 ARM STM STV0991
 M:     Vikas Manocha <vikas.manocha@st.com>

diff --git a/arch/arm/mach-stm32mp/Kconfig b/arch/arm/mach-stm32mp/Kconfig
index a8b09fb..d9ad6b4 100644 (file)
--- a/arch/arm/mach-stm32mp/Kconfig
+++ b/arch/arm/mach-stm32mp/Kconfig
@@ -17,6 +17,7 @@ config SPL
        select SPL_DM_RESET
        select SPL_SERIAL_SUPPORT
        select SPL_SYSCON
+       select SPL_WATCHDOG_SUPPORT
        imply BOOTSTAGE_STASH if SPL_BOOTSTAGE
        imply SPL_BOOTSTAGE if BOOTSTAGE
        imply SPL_DISPLAY_PRINT

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 7a8619f..dbafb74 100644 (file)
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -154,6 +154,14 @@ config WDT_SP805
           Select this to enable SP805 watchdog timer, which can be found on some
           nxp layerscape chips.
 
+config WDT_STM32MP
+       bool "IWDG watchdog driver for STM32 MP's family"
+       depends on WDT
+       imply WATCHDOG
+       help
+         Enable the STM32 watchdog (IWDG) driver. Enable support to
+         configure STM32's on-SoC watchdog.
+
 config XILINX_TB_WATCHDOG
        bool "Xilinx Axi watchdog timer support"
        depends on WDT

diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 6f20e73..e3f4fdb 100644 (file)
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -28,3 +28,4 @@ obj-$(CONFIG_WDT_MPC8xx) += mpc8xx_wdt.o
 obj-$(CONFIG_WDT_MT7621) += mt7621_wdt.o
 obj-$(CONFIG_WDT_MTK) += mtk_wdt.o
 obj-$(CONFIG_WDT_SP805) += sp805_wdt.o
+obj-$(CONFIG_WDT_STM32MP) += stm32mp_wdt.o

diff --git a/drivers/watchdog/stm32mp_wdt.c b/drivers/watchdog/stm32mp_wdt.c
new file mode 100644 (file)
index 0000000..8093d0a
--- /dev/null
+++ b/drivers/watchdog/stm32mp_wdt.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
+/*
+ * Copyright (C) 2019, STMicroelectronics - All Rights Reserved
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <syscon.h>
+#include <wdt.h>
+#include <asm/io.h>
+#include <linux/iopoll.h>
+
+/* IWDG registers */
+#define IWDG_KR                0x00    /* Key register */
+#define IWDG_PR                0x04    /* Prescaler Register */
+#define IWDG_RLR       0x08    /* ReLoad Register */
+#define IWDG_SR                0x0C    /* Status Register */
+
+/* IWDG_KR register bit mask */
+#define KR_KEY_RELOAD  0xAAAA  /* Reload counter enable */
+#define KR_KEY_ENABLE  0xCCCC  /* Peripheral enable */
+#define KR_KEY_EWA     0x5555  /* Write access enable */
+
+/* IWDG_PR register bit values */
+#define PR_256         0x06    /* Prescaler set to 256 */
+
+/* IWDG_RLR register values */
+#define RLR_MAX                0xFFF   /* Max value supported by reload register */
+
+/* IWDG_SR register bit values */
+#define SR_PVU         BIT(0)  /* Watchdog prescaler value update */
+#define SR_RVU         BIT(1)  /* Watchdog counter reload value update */
+
+struct stm32mp_wdt_priv {
+       fdt_addr_t base;                /* registers addr in physical memory */
+       unsigned long wdt_clk_rate;     /* Watchdog dedicated clock rate */
+};
+
+static int stm32mp_wdt_reset(struct udevice *dev)
+{
+       struct stm32mp_wdt_priv *priv = dev_get_priv(dev);
+
+       writel(KR_KEY_RELOAD, priv->base + IWDG_KR);
+
+       return 0;
+}
+
+static int stm32mp_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
+{
+       struct stm32mp_wdt_priv *priv = dev_get_priv(dev);
+       int reload;
+       u32 val;
+       int ret;
+
+       /* Prescaler fixed to 256 */
+       reload = timeout_ms * priv->wdt_clk_rate / 256;
+       if (reload > RLR_MAX + 1)
+               /* Force to max watchdog counter reload value */
+               reload = RLR_MAX + 1;
+       else if (!reload)
+               /* Force to min watchdog counter reload value */
+               reload = priv->wdt_clk_rate / 256;
+
+       /* Set prescaler & reload registers */
+       writel(KR_KEY_EWA, priv->base + IWDG_KR);
+       writel(PR_256, priv->base + IWDG_PR);
+       writel(reload - 1, priv->base + IWDG_RLR);
+
+       /* Enable watchdog */
+       writel(KR_KEY_ENABLE, priv->base + IWDG_KR);
+
+       /* Wait for the registers to be updated */
+       ret = readl_poll_timeout(priv->base + IWDG_SR, val,
+                                val & (SR_PVU | SR_RVU), CONFIG_SYS_HZ);
+
+       if (ret < 0) {
+               pr_err("Updating IWDG registers timeout");
+               return -ETIMEDOUT;
+       }
+
+       return 0;
+}
+
+static int stm32mp_wdt_probe(struct udevice *dev)
+{
+       struct stm32mp_wdt_priv *priv = dev_get_priv(dev);
+       struct clk clk;
+       int ret;
+
+       debug("IWDG init\n");
+
+       priv->base = devfdt_get_addr(dev);
+       if (priv->base == FDT_ADDR_T_NONE)
+               return -EINVAL;
+
+       /* Enable clock */
+       ret = clk_get_by_name(dev, "pclk", &clk);
+       if (ret)
+               return ret;
+
+       ret = clk_enable(&clk);
+       if (ret)
+               return ret;
+
+       /* Get LSI clock */
+       ret = clk_get_by_name(dev, "lsi", &clk);
+       if (ret)
+               return ret;
+
+       priv->wdt_clk_rate = clk_get_rate(&clk);
+
+       debug("IWDG init done\n");
+
+       return 0;
+}
+
+static const struct wdt_ops stm32mp_wdt_ops = {
+       .start = stm32mp_wdt_start,
+       .reset = stm32mp_wdt_reset,
+};
+
+static const struct udevice_id stm32mp_wdt_match[] = {
+       { .compatible = "st,stm32mp1-iwdg" },
+       { /* sentinel */ }
+};
+
+U_BOOT_DRIVER(stm32mp_wdt) = {
+       .name = "stm32mp-wdt",
+       .id = UCLASS_WDT,
+       .of_match = stm32mp_wdt_match,
+       .priv_auto_alloc_size = sizeof(struct stm32mp_wdt_priv),
+       .probe = stm32mp_wdt_probe,
+       .ops = &stm32mp_wdt_ops,
+};