RE: [PATCH 2/6] ARM: at91: pm: use the mmio-sram pool to access SRAM

[Yang, Wenyou]

Hi Alexandre

> -----Original Message-----
> From: linux-arm-kernel [mailto:linux-arm-kernel-bounces@xxxxxxxxxxxxxxxxxxx] On
> Behalf Of Alexandre Belloni
> Sent: Tuesday, January 13, 2015 5:24 AM
> To: Ferre, Nicolas
> Cc: Boris Brezillon; Alexandre Belloni; Jean-Christophe Plagniol-Villard; linux-
> kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Subject: [PATCH 2/6] ARM: at91: pm: use the mmio-sram pool to access SRAM
> 
> Now that the SRAM is part of a genpool, use it to allocate memory to use for the
> slowclock implementation.
> 
> Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
> ---
>  arch/arm/mach-at91/Kconfig |  1 +
>  arch/arm/mach-at91/pm.c    | 46
> +++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig index
> cec0fb5d621a..b7dcef50db23 100644
> --- a/arch/arm/mach-at91/Kconfig
> +++ b/arch/arm/mach-at91/Kconfig
> @@ -178,6 +178,7 @@ comment "AT91 Feature Selections"
> 
>  config AT91_SLOW_CLOCK
>  	bool "Suspend-to-RAM disables main oscillator"
> +	select SRAM
Can we move it under config ARCH_AT91 or other place?

It may be used for other purposes, more than pm. I thinks

>  	depends on SUSPEND
>  	help
>  	  Select this if you want Suspend-to-RAM to save the most power diff --git
> a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c index
> 79aa793d1f00..515791edcc60 100644
> --- a/arch/arm/mach-at91/pm.c
> +++ b/arch/arm/mach-at91/pm.c
> @@ -14,10 +14,12 @@
>  #include <linux/suspend.h>
>  #include <linux/sched.h>
>  #include <linux/proc_fs.h>
> +#include <linux/genalloc.h>
>  #include <linux/interrupt.h>
>  #include <linux/sysfs.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  #include <linux/io.h>
>  #include <linux/clk/at91_pmc.h>
> @@ -222,10 +224,52 @@ void at91_pm_set_standby(void (*at91_standby)(void))
>  	}
>  }
> 
> +#ifdef CONFIG_AT91_SLOW_CLOCK
> +static void __init at91_pm_sram_init(void) {
> +	struct gen_pool *sram_pool;
> +	phys_addr_t sram_pbase;
> +	unsigned long sram_base;
> +	struct device_node *node;
> +	struct platform_device *pdev;
> +
> +	node = of_find_compatible_node(NULL, NULL, "mmio-sram");
> +	if (!node) {
> +		pr_warn("%s: failed to find sram node!\n", __func__);
> +		return;
> +	}
> +
> +	pdev = of_find_device_by_node(node);
> +	if (!pdev) {
> +		pr_warn("%s: failed to find sram device!\n", __func__);
> +		goto put_node;
> +	}
> +
> +	sram_pool = dev_get_gen_pool(&pdev->dev);
> +	if (!sram_pool) {
> +		pr_warn("%s: sram pool unavailable!\n", __func__);
> +		goto put_node;
> +	}
> +
> +	sram_base = gen_pool_alloc(sram_pool, at91_slow_clock_sz);
> +	if (!sram_base) {
> +		pr_warn("%s: unable to alloc ocram!\n", __func__);
> +		goto put_node;
> +	}
> +
> +	sram_pbase = gen_pool_virt_to_phys(sram_pool, sram_base);
> +	slow_clock = __arm_ioremap_exec(sram_pbase, at91_slow_clock_sz,
> +false);
> +
> +put_node:
> +	of_node_put(node);
> +}
> +#endif
> +
> +
>  static int __init at91_pm_init(void)
>  {
>  #ifdef CONFIG_AT91_SLOW_CLOCK
> -	slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz);
> +	at91_pm_sram_init();
>  #endif
> 
>  	pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock
> mode)" : ""));
> --
> 2.1.0
> 
> 
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Best Regards,
Wenyou Yang
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