[PATCH v4 13/21] riscv: Add Canaan Kendryte K210 reset controller

[Damien Le Moal]

On 2020/12/04 19:49, Philipp Zabel wrote:
> Hi Damien,
> 
> On Wed, 2020-12-02 at 12:24 +0900, Damien Le Moal wrote:
>> Add a reset controller driver for the Canaan Kendryte K210 SoC. This
>> driver relies on its syscon compatible parent node (sysctl) for its
>> register mapping. Automatically select this driver for compilation
>> when the SOC_CANAAN option is selected.
>>
>> The MAINTAINERS file is updated, adding the entry "CANAAN/KENDRYTE K210
>> SOC RESET CONTROLLER DRIVER" with myself listed as maintainer for this
>> driver.
>>
>> Signed-off-by: Damien Le Moal <damien.lemoal at wdc.com>
>> ---
>>  MAINTAINERS                |   8 +++
>>  arch/riscv/Kconfig.socs    |   3 +
>>  drivers/reset/Kconfig      |   9 +++
>>  drivers/reset/Makefile     |   1 +
>>  drivers/reset/reset-k210.c | 141 +++++++++++++++++++++++++++++++++++++
>>  5 files changed, 162 insertions(+)
>>  create mode 100644 drivers/reset/reset-k210.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index a059ab02fa8a..c2b3d6e48cd5 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -3837,6 +3837,14 @@ L:	linux-gpio at vger.kernel.org (pinctrl driver)
>>  F:	Documentation/devicetree/bindings/pinctrl/canaan,k210-fpioa.yaml
>>  F:	drivers/pinctrl/pinctrl-k210.c
>>  
>> +CANAAN/KENDRYTE K210 SOC RESET CONTROLLER DRIVER
>> +M:	Damien Le Moal <damien.lemoal at wdc.com>
>> +L:	linux-kernel at vger.kernel.org
>> +L:	linux-riscv at lists.infradead.org
>> +S:	Maintained
>> +F:	Documentation/devicetree/bindings/reset/canaan,k210-rst.yaml
>> +F:	drivers/reset/reset-k210.c
>> +
>>  CANAAN/KENDRYTE K210 SOC SYSTEM CONTROLLER DRIVER
>>  M:	Damien Le Moal <damien.lemoal at wdc.com>
>>  L:	linux-riscv at lists.infradead.org
>> diff --git a/arch/riscv/Kconfig.socs b/arch/riscv/Kconfig.socs
>> index 68bdd664b5c2..b3cd253ec2c2 100644
>> --- a/arch/riscv/Kconfig.socs
>> +++ b/arch/riscv/Kconfig.socs
>> @@ -33,6 +33,9 @@ config SOC_CANAAN
>>  	select CLK_K210
>>  	select PINCTRL
>>  	select PINCTRL_K210
>> +	select ARCH_HAS_RESET_CONTROLLER
>> +	select RESET_CONTROLLER
>> +	select RESET_K210
>>  	help
>>  	  This enables support for Canaan Kendryte K210 SoC platform hardware.
>>  
>> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
>> index 07d162b179fc..529d206cfdfd 100644
>> --- a/drivers/reset/Kconfig
>> +++ b/drivers/reset/Kconfig
>> @@ -245,6 +245,15 @@ config RESET_ZYNQ
>>  	help
>>  	  This enables the reset controller driver for Xilinx Zynq SoCs.
>>  
>> +config RESET_K210
>> +	bool "Reset controller driver for Canaan Kendryte K210 SoC"
>> +	depends on RISCV && SOC_CANAAN
>> +	depends on OF && MFD_SYSCON
>> +	help
>> +	  Support for the Canaan Kendryte K210 RISC-V SoC reset controller.
>> +	  Say Y if you want to control reset signals provided by this
>> +	  controller.
>> +
>>  source "drivers/reset/sti/Kconfig"
>>  source "drivers/reset/hisilicon/Kconfig"
>>  source "drivers/reset/tegra/Kconfig"
>> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
>> index 16947610cc3b..1730a31e6871 100644
>> --- a/drivers/reset/Makefile
>> +++ b/drivers/reset/Makefile
>> @@ -33,4 +33,5 @@ obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
>>  obj-$(CONFIG_RESET_UNIPHIER_GLUE) += reset-uniphier-glue.o
>>  obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o
>>  obj-$(CONFIG_ARCH_ZYNQMP) += reset-zynqmp.o
>> +obj-$(CONFIG_RESET_K210) += reset-k210.o
>>  
>> diff --git a/drivers/reset/reset-k210.c b/drivers/reset/reset-k210.c
>> new file mode 100644
>> index 000000000000..2cf9a63c763d
>> --- /dev/null
>> +++ b/drivers/reset/reset-k210.c
>> @@ -0,0 +1,141 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * Copyright (c) 2020 Western Digital Corporation or its affiliates.
>> + */
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset-controller.h>
>> +#include <linux/delay.h>
>> +#include <linux/mfd/syscon.h>
>> +#include <linux/regmap.h>
>> +#include <soc/canaan/k210-sysctl.h>
>> +
>> +#include <dt-bindings/reset/k210-rst.h>
>> +
>> +#define K210_RST_MASK	0x27FFFFFF
>> +
>> +struct k210_rst {
>> +	struct regmap *map;
>> +	struct reset_controller_dev rcdev;
>> +};
>> +
>> +static inline struct k210_rst *
>> +to_k210_rst(struct reset_controller_dev *rcdev)
>> +{
>> +	return container_of(rcdev, struct k210_rst, rcdev);
>> +}
>> +
>> +static inline int k210_rst_assert(struct reset_controller_dev *rcdev,
>> +				  unsigned long id)
>> +{
>> +	struct k210_rst *ksr = to_k210_rst(rcdev);
>> +	u32 bit = BIT(id);
>> +
>> +	if (!(bit & K210_RST_MASK))
>> +		return -EINVAL;
> 
> Instead of checking this mask in the k210_rst_assert/deassert/status()
> functions, you could implement a custom .of_xlate callback and disallow
> requesting invalid resets in the first place.

OK. I did not know about this. Will look into it and send a v5.

Thanks !

> 
> regards
> Philipp
> 


-- 
Damien Le Moal
Western Digital Research