linux-kernel - Re: [PATCH] reset: socfpga: add an early reset driver for SoCFPGA

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Date:   Thu, 04 Oct 2018 11:53:56 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Dinh Nguyen <dinguyen@...nel.org>
Cc:     marex@...x.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] reset: socfpga: add an early reset driver for SoCFPGA

Hi Dinh,

On Mon, 2018-09-17 at 09:50 -0500, Dinh Nguyen wrote:
> Create a separate reset driver that uses the reset operations in reset-simple.
> The reset driver for the SoCFPGA platform needs to register early in order to
> be able bring online timers that needed early in the kernel bootup.
> 
> Signed-off-by: Dinh Nguyen <dinguyen@...nel.org>
> ---
>  arch/arm/mach-socfpga/socfpga.c |  4 ++
>  drivers/reset/Kconfig           |  7 ++++
>  drivers/reset/Makefile          |  1 +
>  drivers/reset/reset-simple.c    | 17 ---------
>  drivers/reset/reset-socfpga.c   | 85 +++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 97 insertions(+), 17 deletions(-)
>  create mode 100644 drivers/reset/reset-socfpga.c
> 
> diff --git a/arch/arm/mach-socfpga/socfpga.c b/arch/arm/mach-socfpga/socfpga.c
> index dde14f7..cc64576 100644
> --- a/arch/arm/mach-socfpga/socfpga.c
> +++ b/arch/arm/mach-socfpga/socfpga.c
> @@ -32,6 +32,8 @@ void __iomem *rst_manager_base_addr;
>  void __iomem *sdr_ctl_base_addr;
>  unsigned long socfpga_cpu1start_addr;
>  
> +extern void __init socfpga_reset_init(void);
> +
>  void __init socfpga_sysmgr_init(void)
>  {
>  	struct device_node *np;
> @@ -64,6 +66,7 @@ static void __init socfpga_init_irq(void)
>  
>  	if (IS_ENABLED(CONFIG_EDAC_ALTERA_OCRAM))
>  		socfpga_init_ocram_ecc();
> +	socfpga_reset_init();
>  }
>  
>  static void __init socfpga_arria10_init_irq(void)
> @@ -74,6 +77,7 @@ static void __init socfpga_arria10_init_irq(void)
>  		socfpga_init_arria10_l2_ecc();
>  	if (IS_ENABLED(CONFIG_EDAC_ALTERA_OCRAM))
>  		socfpga_init_arria10_ocram_ecc();
> +	socfpga_reset_init();
>  }
>  
>  static void socfpga_cyclone5_restart(enum reboot_mode mode, const char *cmd)
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index 13d28fd..dcc5f1d 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -119,6 +119,13 @@ config RESET_STM32MP157
>  	help
>  	  This enables the RCC reset controller driver for STM32 MPUs.
>  
> +config RESET_SOCFPGA
> +	bool "SoCFPGA Reset Driver" if COMPILE_TEST && !ARCH_SOCFPGA
> +	default ARCH_SOCFPGA
> +	select RESET_SIMPLE
> +	help
> +	  This enables the reset driver for SoCFPGA.
> +
>  config RESET_SUNXI
>  	bool "Allwinner SoCs Reset Driver" if COMPILE_TEST && !ARCH_SUNXI
>  	default ARCH_SUNXI
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index 4243c38..d09bb41 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -18,6 +18,7 @@ obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
>  obj-$(CONFIG_RESET_QCOM_AOSS) += reset-qcom-aoss.o
>  obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o
>  obj-$(CONFIG_RESET_STM32MP157) += reset-stm32mp1.o
> +obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o
>  obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
>  obj-$(CONFIG_RESET_TI_SCI) += reset-ti-sci.o
>  obj-$(CONFIG_RESET_TI_SYSCON) += reset-ti-syscon.o
> diff --git a/drivers/reset/reset-simple.c b/drivers/reset/reset-simple.c
> index a91107f..483824f 100644
> --- a/drivers/reset/reset-simple.c
> +++ b/drivers/reset/reset-simple.c
> @@ -106,21 +106,12 @@ struct reset_simple_devdata {
>  	bool status_active_low;
>  };
>  
> -#define SOCFPGA_NR_BANKS	8
> -
> -static const struct reset_simple_devdata reset_simple_socfpga = {
> -	.reg_offset = 0x10,

Before, the default reg_offset for DTs missing the altr,modrst-offset
property was 0x10 ...

> -	.nr_resets = SOCFPGA_NR_BANKS * 32,
> -	.status_active_low = true,
> -};
> -
[...]
> +static int a10_reset_init(struct device_node *np)
> +{
> +	struct reset_simple_data *data;
> +	struct resource res;
> +	resource_size_t size;
> +	int ret;
> +	u32 reg_offset = 0;

... now it is 0x0.
I think this should be

	u32 reg_offset = 0x10;

to avoid breaking SocFPGA with ancient device trees.

> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	ret = of_address_to_resource(np, 0, &res);
> +	if (ret)
> +		goto err_alloc;
> +
> +	size = resource_size(&res);
> +	if (!request_mem_region(res.start, size, np->name)) {
> +		ret = -EBUSY;
> +		goto err_alloc;
> +	}
> +
> +	data->membase = ioremap(res.start, size);
> +	if (!data->membase) {
> +		ret = -ENOMEM;
> +		goto err_alloc;
> +	}
> +
> +	if (of_property_read_u32(np, "altr,modrst-offset", &reg_offset))
> +		pr_warn("missing altr,modrst-offset property, assuming 0x0\n");
> +	data->membase += reg_offset;
> +
> +	spin_lock_init(&data->lock);
> +
> +	data->rcdev.owner = THIS_MODULE;
> +	data->rcdev.nr_resets = 32 * 8;

Could we keep the SOCFPGA_NR_BANKS #define to reduce the amount of magic
numbers?

I can make both changes when applying if you want.

regards
Philipp