Subject: [PATCH v2 06/10] ARM: EXYNOS: Add support for mapping PMU base address via DT

From: [email-masked] (Tomasz Figa)
Date: Fri, 25 Apr 2014 23:43:43 +0200

Hi,

On 25.04.2014 14:32, Pankaj Dubey wrote:
> From: Young-Gun Jang <[email-masked]>
>
> Add support for mapping Samsung Power Management Unit (PMU) base address
> from device tree. Code will use existing samsung pmu binding information.
> This patch also adds two helper functions as "get_exynos_pmuregmap" and
> "get_exynos_pmuaddr".
> "get_exynos_pmuregmap" returns a regmap based PMU register handle where as
> "get_exynos_pmuaddr" returns ioremap virtual address.
>
> Signed-off-by: Young-Gun Jang <[email-masked]>
> Signed-off-by: Pankaj Dubey <[email-masked]>
> ---
>   arch/arm/mach-exynos/Kconfig  |    2 ++
>   arch/arm/mach-exynos/common.h |    3 ++
>   arch/arm/mach-exynos/exynos.c |   78 +++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 83 insertions(+)
>
> diff --git a/arch/arm/mach-exynos/Kconfig b/arch/arm/mach-exynos/Kconfig
> index fc8bf18..2f60c90 100644
> --- a/arch/arm/mach-exynos/Kconfig
> +++ b/arch/arm/mach-exynos/Kconfig
> @@ -26,6 +26,7 @@ config ARCH_EXYNOS4
>   	select PINCTRL
>   	select PM_GENERIC_DOMAINS if PM_RUNTIME
>   	select S5P_DEV_MFC
> +	select MFD_SYSCON
>   	help
>   	  Samsung EXYNOS4 SoCs based systems
>
> @@ -36,6 +37,7 @@ config ARCH_EXYNOS5
>   	select HAVE_ARM_SCU if SMP
>   	select HAVE_SMP
>   	select PINCTRL
> +	select MFD_SYSCON
>   	help
>   	  Samsung EXYNOS5 (Cortex-A15) SoC based systems
>
> diff --git a/arch/arm/mach-exynos/common.h b/arch/arm/mach-exynos/common.h
> index 31c5964..ecfd0fc 100644
> --- a/arch/arm/mach-exynos/common.h
> +++ b/arch/arm/mach-exynos/common.h
> @@ -57,4 +57,7 @@ struct exynos_pmu_conf {
>
>   extern void exynos_sys_powerdown_conf(enum sys_powerdown mode);
>
> +extern struct regmap *get_exynos_pmuregmap(void);
> +extern void __iomem *get_exynos_pmuaddr(void);

Do you really need these functions? Couldn't all the drivers using PMU 
simply call syscon_regmap_lookup_by_phandle() or of_iomap() directly?

> +
>   #endif /* __ARCH_ARM_MACH_EXYNOS_COMMON_H */
> diff --git a/arch/arm/mach-exynos/exynos.c b/arch/arm/mach-exynos/exynos.c
> index d6f405f..68f60e1 100644
> --- a/arch/arm/mach-exynos/exynos.c
> +++ b/arch/arm/mach-exynos/exynos.c
> @@ -19,6 +19,7 @@
>   #include <linux/of_platform.h>
>   #include <linux/platform_device.h>
>   #include <linux/pm_domain.h>
> +#include <linux/mfd/syscon.h>
>
>   #include <asm/cacheflush.h>
>   #include <asm/hardware/cache-l2x0.h>
> @@ -36,6 +37,9 @@
>   #define L2_AUX_VAL 0x7C470001
>   #define L2_AUX_MASK 0xC200ffff
>
> +static struct regmap *exynos_pmu_regmap;
> +static void __iomem *exynos_pmu_base;
> +
>   static struct map_desc exynos4_iodesc[] __initdata = {
>   	{
>   		.virtual	= (unsigned long)S3C_VA_SYS,
> @@ -269,6 +273,46 @@ static int __init exynos_fdt_map_chipid(unsigned long node, const char *uname,
>   	return 1;
>   }
>
> +static const struct of_device_id exynos_dt_pmu_match[] = {
> +	{ .compatible = "samsung,exynos4210-pmu" },
> +	{ .compatible = "samsung,exynos4212-pmu" },
> +	{ .compatible = "samsung,exynos4412-pmu" },
> +	{ .compatible = "samsung,exynos5250-pmu" },
> +	{},
> +};
> +
> +static int __init exynos_fdt_map_pmu(unsigned long node,
> +		const char *uname, int depth, void *data)
> +{
> +	struct map_desc iodesc;
> +	__be32 *reg;
> +	unsigned long len;
> +	phys_addr_t phys_addr;
> +	const struct of_device_id *matches = exynos_dt_pmu_match;
> +
> +	for (; matches->compatible[0]; matches++) {
> +		if (!of_flat_dt_is_compatible(node, matches->compatible))
> +			continue;
> +		reg = of_get_flat_dt_prop(node, "reg", &len);
> +		if (reg == NULL || len != (sizeof(unsigned long) * 2))
> +			return 0;
> +
> +		phys_addr = be32_to_cpu(reg[0]);
> +		iodesc.pfn = __phys_to_pfn(phys_addr);
> +		iodesc.length = be32_to_cpu(reg[1]) - 1;
> +		iodesc.virtual = (unsigned long)S5P_VA_PMU;
> +		iodesc.type = MT_DEVICE;
> +		iotable_init(&iodesc, 1);
> +
> +		exynos_pmu_base = ioremap(phys_addr, be32_to_cpu(reg[1]));
> +		if (WARN_ON(!exynos_pmu_base))
> +			return -EFAULT;
> +		return 1;
> +	}
> +
> +	return 0;
> +}

Is such early mapping really needed? Couldn't the code using PMU be 
deferred to the stage that memory management is available and then 
of_iomap() used directly?

> +
>   /*
>    * exynos_map_io
>    *
> @@ -302,6 +346,7 @@ static void __init exynos_init_io(void)
>   	debug_ll_io_init();
>
>   	of_scan_flat_dt(exynos_fdt_map_chipid, NULL);
> +	of_scan_flat_dt(exynos_fdt_map_pmu, NULL);
>
>   	/* detect cpu id and rev. */
>   	s5p_init_cpu(S5P_VA_CHIPID);
> @@ -336,6 +381,38 @@ static int __init exynos4_l2x0_cache_init(void)
>   }
>   early_initcall(exynos4_l2x0_cache_init);
>
> +
> +inline struct regmap *get_exynos_pmuregmap()
> +{
> +	return exynos_pmu_regmap;
> +}
> +
> +inline void __iomem *get_exynos_pmuaddr()
> +{
> +	return exynos_pmu_base;
> +}

Hmm, non-static inline inside a C file? Probably should be either static 
inline or non-static non-inline. (Assuming that both are really needed, 
as I pointed in the comments above.)

> +
> +
> +void __init exynos_map_pmu(void)
> +{
> +	struct device_node *np = NULL;
> +
> +	early_syscon_init();
> +
> +	np = of_find_matching_node(NULL, exynos_dt_pmu_match);
> +
> +	if (!np) {
> +		pr_err("Failed to find PMU node\n");
> +		return;
> +	} else {
> +		exynos_pmu_regmap = syscon_early_regmap_lookup_by_phandle(np,
> +				"samsung,syscon-phandle");

Do you need this regmap really here? I believe it should be the code 
using PMU registers which calls this function directly to retrieve a 
handle to the syscon.

Best regards,
Tomasz