Subject: [PATCH 5/5] ARM: bcm4760: Add restart hook

From: [email-masked] (Arnd Bergmann)
Date: Sun, 21 Jul 2013 10:20:25 +0200

On Sunday 21 July 2013, Domenico Andreoli wrote:
> From: Domenico Andreoli <[email-masked]>
> 
> Restart hook implementation for the Broadcom BCM4760 based ARM11 SoCs.
> 
> Cc: linux-arm-kernel at lists.infradead.org
> Signed-off-by: Domenico Andreoli <[email-masked]>
> ---
>  Documentation/devicetree/bindings/watchdog/brcm,bcm4760-pm-wdt.txt |   14 ++
>  arch/arm/boot/dts/bcm4760.dtsi                                     |    5 +
>  arch/arm/mach-bcm/bcm4760.c                                        |   78 ++++++++++
>  3 files changed, 97 insertions(+)

The implementation looks ok to me, but I would prefer this to be part of a
watchdog device driver that overrides the pm_power_off hook.

It can probably be done at a later stage when you submit a watchdog driver.

	Arnd

> Index: b/Documentation/devicetree/bindings/watchdog/brcm,bcm4760-pm-wdt.txt
> ===================================================================
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/brcm,bcm4760-pm-wdt.txt
> @@ -0,0 +1,14 @@
> +Broadcom BCM4760 watchdog timer device tree bindings
> +----------------------------------------------------
> +
> +Required properties:
> +
> +- compatible : should be "brcm,bcm4760-pm-wdt"
> +- reg : Specifies base physical address and size of the registers.
> +
> +Example:
> +
> +watchdog {
> +	compatible = "brcm,bcm4760-pm-wdt";
> +	reg = <0xbd000 0x1000>;
> +};
> Index: b/arch/arm/boot/dts/bcm4760.dtsi
> ===================================================================
> --- a/arch/arm/boot/dts/bcm4760.dtsi
> +++ b/arch/arm/boot/dts/bcm4760.dtsi
> @@ -23,6 +23,11 @@
>  			reg = <0xbc000 0x1000>;
>  		};
>  
> +		watchdog {
> +			compatible = "brcm,bcm4760-pm-wdt";
> +			reg = <0xbd000 0x1000>;
> +		};
> +
>  		vic0: interrupt-controller at 80000 {
>  			compatible = "brcm,bcm4760-pl192", "arm,pl192-vic", "arm,primecell";
>  			reg = <0x80000 0x1000>;
> Index: b/arch/arm/mach-bcm/bcm4760.c
> ===================================================================
> --- a/arch/arm/mach-bcm/bcm4760.c
> +++ b/arch/arm/mach-bcm/bcm4760.c
> @@ -16,7 +16,9 @@
>  
>  #include <linux/init.h>
>  #include <linux/irqchip.h>
> +#include <linux/delay.h>
>  #include <linux/of_irq.h>
> +#include <linux/of_address.h>
>  #include <linux/of_platform.h>
>  #include <linux/clk/bcm4760.h>
>  
> @@ -28,6 +30,17 @@
>  #define BCM4760_PERIPH_VIRT   IOMEM(0xd0080000)
>  #define BCM4760_PERIPH_SIZE   SZ_512K
>  
> +#define BCM4760_WDT_LOAD      0x000
> +#define BCM4760_WDT_CTRL      0x008
> +#define BCM4760_WDT_INTCLR    0x00c
> +#define BCM4760_WDT_LOCK      0xc00
> +
> +#define BCM4760_WDT_PASSWORD  0x1acce551
> +#define BCM4760_WDT_INTEN     BIT(0)
> +#define BCM4760_WDT_RESEN     BIT(1)
> +
> +static void __iomem *wdt_regs;
> +
>  static struct map_desc io_map __initdata = {
>  	.virtual = (unsigned long) BCM4760_PERIPH_VIRT,
>  	.pfn = __phys_to_pfn(BCM4760_PERIPH_PHYS),
> @@ -56,11 +69,75 @@ static void __init bcm4760_system_rev(vo
>  		system_rev = id0 << 8 | (id1 & 0xff);
>  }
>  
> +static const struct of_device_id bcm4760_pm_wdt_match[] __initconst = {
> +	{ .compatible = "brcm,bcm4760-pm-wdt" },
> +	{}
> +};
> +
> +/*
> + * The machine restart method can be called from an atomic context so we won't
> + * be able to ioremap the regs then.
> + */
> +static void __init bcm4760_setup_restart(void)
> +{
> +	struct device_node *node;
> +
> +	node = of_find_matching_node(NULL, bcm4760_pm_wdt_match);
> +	if (!node) {
> +		pr_info("No bcm4760 watchdog node\n");
> +		return;
> +	}
> +
> +	wdt_regs = of_iomap(node, 0);
> +	if (!wdt_regs) {
> +		pr_err("Can't remap watchdog registers\n");
> +		return;
> +	}
> +
> +	/* unlock watchdog registers */
> +	writel(BCM4760_WDT_PASSWORD, wdt_regs + BCM4760_WDT_LOCK);
> +	/* disable watchdog */
> +	writel(0, wdt_regs + BCM4760_WDT_CTRL);
> +	/* lock watchdog registers */
> +	writel(1, wdt_regs + BCM4760_WDT_LOCK);
> +}
> +
> +static void bcm4760_restart(enum reboot_mode mode, const char *cmd)
> +{
> +	if (!wdt_regs) {
> +		pr_err("No restart hook installed. ");
> +		return;
> +	}
> +
> +	/* unlock watchdog registers */
> +	writel(BCM4760_WDT_PASSWORD, wdt_regs + BCM4760_WDT_LOCK);
> +
> +	/* disable watchdog */
> +	writel(0, wdt_regs + BCM4760_WDT_CTRL);
> +	udelay(20);
> +
> +	/* clear the irq status */
> +	writel(1, wdt_regs + BCM4760_WDT_INTCLR);
> +	udelay(20);
> +
> +	/* expire after 5 cycles (~156us) */
> +	writel(5, wdt_regs + BCM4760_WDT_LOAD);
> +	/* enable watchdog */
> +	writel(BCM4760_WDT_INTEN | BCM4760_WDT_RESEN,
> +		wdt_regs + BCM4760_WDT_CTRL);
> +
> +	/* lock watchdog registers */
> +	writel(1, wdt_regs + BCM4760_WDT_LOCK);
> +	/* wait the bite */
> +	udelay(400);
> +}
> +
>  static void __init bcm4760_init(void)
>  {
>  	int err;
>  
>  	bcm4760_system_rev();
> +	bcm4760_setup_restart();
>  	bcm4760_init_clocks();
>  
>  	err = of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
> @@ -78,5 +155,6 @@ static const char * const bcm4760_compat
>  DT_MACHINE_START(BCM4760, "Broadcom BCM4760")
>  	.map_io = bcm4760_map_io,
>  	.init_machine = bcm4760_init,
> +	.restart = bcm4760_restart,
>  	.dt_compat = bcm4760_compat
>  MACHINE_END
> 
>