Re: [PATCH v1 04/14] reset: add polarfire soc reset support

Conor.Dooley
2022-06-30T16:20:33Z

On 30/06/2022 10:12, Philipp Zabel wrote:

(This came to me oddly quoted, so I have fixed it myself)

>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>
>> Hi Conor,
>>
>> On Do, 2022-06-30 at 09:05 +0100, Conor Dooley wrote:
>> Add support for the resets on Microchip's PolarFire SoC (MPFS).
>> Reset control is a single register, wedged in between registers for
>> clock control. To fit with existed DT etc, the reset controller is
>>
> existing ^
>>
>> created using the aux device framework & set up in the clock driver.
>>
>> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
>> ---
>> drivers/reset/Kconfig | 9 +++
>> drivers/reset/Makefile | 2 +-
>> drivers/reset/reset-mpfs.c | 145 +++++++++++++++++++++++++++++++++++++
>> 3 files changed, 155 insertions(+), 1 deletion(-)
>> create mode 100644 drivers/reset/reset-mpfs.c
>>
>> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
>> index 93c8d07ee328..edf48951f763 100644
>> --- a/drivers/reset/Kconfig
>> +++ b/drivers/reset/Kconfig
>> @@ -122,6 +122,15 @@ config RESET_MCHP_SPARX5
>> help
>> This driver supports switch core reset for the Microchip Sparx5 SoC.
>>
>>
>> +config RESET_POLARFIRE_SOC
>> + bool "Microchip PolarFire SoC (MPFS) Reset Driver"
>> + depends on AUXILIARY_BUS && MCHP_CLK_MPFS
>> + default MCHP_CLK_MPFS
>> + help
>> + This driver supports peripheral reset for the Microchip PolarFire SoC
>> +
>> + CONFIG_RESET_MPFS
>>
>This doesn't look intentional.

Correct. I fixed it when rebasing on -next and forgot to re-fix it
when I had to reset back to -rc2...

>>
>> +
>> config RESET_MESON
>> tristate "Meson Reset Driver"
>> depends on ARCH_MESON || COMPILE_TEST
>> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
>> index a80a9c4008a7..5fac3a753858 100644
>> --- a/drivers/reset/Makefile
>> +++ b/drivers/reset/Makefile
>> @@ -17,6 +17,7 @@ obj-$(CONFIG_RESET_K210) += reset-k210.o
>> obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
>> obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
>> obj-$(CONFIG_RESET_MCHP_SPARX5) += reset-microchip-sparx5.o
>> +obj-$(CONFIG_RESET_POLARFIRE_SOC) += reset-mpfs.o
>> obj-$(CONFIG_RESET_MESON) += reset-meson.o
>> obj-$(CONFIG_RESET_MESON_AUDIO_ARB) += reset-meson-audio-arb.o
>> obj-$(CONFIG_RESET_NPCM) += reset-npcm.o
>> @@ -38,4 +39,3 @@ 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
>> -
>> diff --git a/drivers/reset/reset-mpfs.c b/drivers/reset/reset-mpfs.c
>> new file mode 100644
>> index 000000000000..49c47a3e6c70
>> --- /dev/null
>> +++ b/drivers/reset/reset-mpfs.c
>> @@ -0,0 +1,145 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * PolarFire SoC (MPFS) Peripheral Clock Reset Controller
>> + *
>> + * Author: Conor Dooley <conor.dooley@microchip.com>
>> + * Copyright (c) 2022 Microchip Technology Inc. and its subsidiaries.
>> + *
>> + */
>> +#include <linux/auxiliary_bus.h>
>> +#include <linux/delay.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset-controller.h>
>> +#include <dt-bindings/clock/microchip,mpfs-clock.h>
>> +#include <soc/microchip/mpfs.h>
>> +
>> +/*
>> + * The ENVM reset is the lowest bit in the register & I am using the CLK_FOO
>> + * defines in the dt to make things easier to configure - so this is accounting
>> + * for the offset of 3 there.
>> + */
>> +#define MPFS_PERIPH_OFFSET CLK_ENVM
>> +#define MPFS_NUM_RESETS 30u
>> +#define MPFS_SLEEP_MIN_US 100
>> +#define MPFS_SLEEP_MAX_US 200
>> +
>> +/*
>> + * Peripheral clock resets
>> + */
>> +
>> +static int mpfs_assert(struct reset_controller_dev *rcdev, unsigned long id)
>> +{
>> + u32 reg;
>> +
>> + reg = mpfs_reset_read(rcdev->dev);
>> + reg |= (1u << id);
>> + mpfs_reset_write(rcdev->dev, reg);
>
> This is missing a spinlock to protect against concurrent read-modify-
> writes.
>>
>> +
>> + return 0;
>> +}
>> +
>> +static int mpfs_deassert(struct reset_controller_dev *rcdev, unsigned long id)
>> +{
>> + u32 reg, val;
>> +
>> + reg = mpfs_reset_read(rcdev->dev);
>> + val = reg & ~(1u << id);
>
> You could use BIT(id) instead of (1u << id).
>
>> + mpfs_reset_write(rcdev->dev, val);
>> +
>> + return 0;
>> +}
>> +
>> +static int mpfs_status(struct reset_controller_dev *rcdev, unsigned long id)
>> +{
>> + u32 reg = mpfs_reset_read(rcdev->dev);
>> +
>> + return (reg & (1u << id));
>
> Side note, this works because MPFS_NUM_RESETS makes sure the sign bit
> is never hit.

I can add a comment to that effect if you want?

>>
>> +}
>> +
>> +static int mpfs_reset(struct reset_controller_dev *rcdev, unsigned long id)
>> +{
>> + mpfs_assert(rcdev, id);
>> +
>> + usleep_range(MPFS_SLEEP_MIN_US, MPFS_SLEEP_MAX_US);
>> +
>> + mpfs_deassert(rcdev, id);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct reset_control_ops mpfs_reset_ops = {
>> + .reset = mpfs_reset,
>> + .assert = mpfs_assert,
>> + .deassert = mpfs_deassert,
>> + .status = mpfs_status,
>> +};
>> +
>> +static int mpfs_reset_xlate(struct reset_controller_dev *rcdev,
>> + const struct of_phandle_args *reset_spec)
>> +{
>> + unsigned int index = reset_spec->args[0];
>> +
>> + /*
>> + * CLK_RESERVED does not map to a clock, but it does map to a reset,
>> + * so it has to be accounted for here. It is the reset for the fabric,
>> + * so if this reset gets called - do not reset it.
>> + */
>> + if (index == CLK_RESERVED) {
>> + dev_err(rcdev->dev, "Resetting the fabric is not supported\n");
>> + return -EINVAL;
>> + }
>> +
>> + if (index < MPFS_PERIPH_OFFSET || index >= (MPFS_PERIPH_OFFSET + rcdev->nr_resets)) {
>> + dev_err(rcdev->dev, "Invalid reset index %u\n", reset_spec->args[0]);
>
> s/reset_spec->args[0]/index/
>
>> + return -EINVAL;
>> + }
>> +
>> + return index - MPFS_PERIPH_OFFSET;
>> +}
>> +
>> +static int mpfs_reset_probe(struct auxiliary_device *adev,
>> + const struct auxiliary_device_id *id)
>> +{
>> + struct device *dev = &adev->dev;
>> + struct reset_controller_dev *rcdev;
>> + int ret;
>> +
>> + rcdev = devm_kzalloc(dev, sizeof(*rcdev), GFP_KERNEL);
>> + if (!rcdev)
>> + return -ENOMEM;
>> +
>> + rcdev->dev = dev;
>> + rcdev->dev->parent = adev->dev.parent;
>>
>> s/adev->dev./dev->/
>>
>> + rcdev->ops = &mpfs_reset_ops;
>> + rcdev->of_node = adev->dev.parent->of_node;
>>
>> s/adev->dev./dev->/
>>
>> + rcdev->of_reset_n_cells = 1;
>> + rcdev->of_xlate = mpfs_reset_xlate;
>> + rcdev->nr_resets = MPFS_NUM_RESETS;
>> +
>> + ret = devm_reset_controller_register(dev, rcdev);
>> + if (!ret)
>> + dev_info(dev, "Registered MPFS reset controller\n");
>
> Is this really useful information for most users?

Probably not, but it is useful for my CI haha.
If you don't like it, I will remove it.

>
>> +
>> + return ret;
>> +}
>> +
>> +static const struct auxiliary_device_id mpfs_reset_ids[] = {
>> + {
>> + .name = "clk_mpfs.reset-mpfs",
>> + },
>> + { }
>> +};
>> +MODULE_DEVICE_TABLE(auxiliary, mpfs_reset_ids);
>> +
>> +static struct auxiliary_driver mpfs_reset_driver = {
>> + .probe = mpfs_reset_probe,
>> + .id_table = mpfs_reset_ids,
>> +};
>> +
>> +module_auxiliary_driver(mpfs_reset_driver);
>> +
>> +MODULE_DESCRIPTION("Microchip PolarFire SoC Reset Driver");
>> +MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
>> +MODULE_LICENSE("GPL");
>> +MODULE_IMPORT_NS(MCHP_CLK_MPFS);
>>
> regards
> Philipp