Re: [PATCH v2 2/6] reset: qcom: PDC Global (Power Domain Controller) reset controller

[Matthias Kaehlcke <mka@chromium.org>]

Hi Sibi,

On Fri, Aug 24, 2018 at 06:48:56PM +0530, Sibi Sankar wrote:
> Add reset controller for SDM845 SoCs to control reset signals provided
> by PDC Global for Modem, Compute, Display, GPU, Debug, AOP, Sensors,
> Audio, SP and APPS
> 
> Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
> ---
>  drivers/reset/Kconfig          |   9 +++
>  drivers/reset/Makefile         |   1 +
>  drivers/reset/reset-qcom-pdc.c | 142 +++++++++++++++++++++++++++++++++
>  3 files changed, 152 insertions(+)
>  create mode 100644 drivers/reset/reset-qcom-pdc.c
> 
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index 13d28fdbdbb5..c21da9fe51ec 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -98,6 +98,15 @@ config RESET_QCOM_AOSS
>  	  reset signals provided by AOSS for Modem, Venus, ADSP,
>  	  GPU, Camera, Wireless, Display subsystem. Otherwise, say N.
>  
> +config RESET_QCOM_PDC
> +	tristate "Qualcomm PDC Reset Driver"
> +	depends on ARCH_QCOM || COMPILE_TEST
> +	help
> +	  This enables the PDC (Power Domain Controller) reset driver
> +	  for Qualcomm Technologies Inc SDM845 SoCs. Say Y if you want
> +	  to control reset signals provided by PDC for Modem, Compute,
> +	  Display, GPU, Debug, AOP, Sensors, Audio, SP and APPS.

What exactly does APPS mean? The AP cores, the entire SoC, something
else?

> +
>  config RESET_SIMPLE
>  	bool "Simple Reset Controller Driver" if COMPILE_TEST
>  	default ARCH_SOCFPGA || ARCH_STM32 || ARCH_STRATIX10 || ARCH_SUNXI || ARCH_ZX || ARCH_ASPEED
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index 4243c38228e2..d08e8b90046a 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_RESET_MESON_AUDIO_ARB) += reset-meson-audio-arb.o
>  obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
>  obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
>  obj-$(CONFIG_RESET_QCOM_AOSS) += reset-qcom-aoss.o
> +obj-$(CONFIG_RESET_QCOM_PDC) += reset-qcom-pdc.o
>  obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o
>  obj-$(CONFIG_RESET_STM32MP157) += reset-stm32mp1.o
>  obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
> diff --git a/drivers/reset/reset-qcom-pdc.c b/drivers/reset/reset-qcom-pdc.c
> new file mode 100644
> index 000000000000..bb6a5e5ee0f8
> --- /dev/null
> +++ b/drivers/reset/reset-qcom-pdc.c
> @@ -0,0 +1,142 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2018 The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
> +#include <linux/regmap.h>
> +#include <linux/of_device.h>
> +#include <dt-bindings/reset/qcom,sdm845-pdc.h>

Headers should be sorted in alphabetical order.

> +
> +#define RPMH_PDC_SYNC_RESET	0x100
> +
> +struct qcom_pdc_reset_map {
> +	u8 bit;
> +};
> +
> +struct qcom_pdc_desc {
> +	const struct regmap_config *config;
> +	const struct qcom_pdc_reset_map *resets;
> +	size_t num_resets;
> +};

Not sure if this structure adds much value or just a layer of
indirection:

- .config is only accessed in _probe(), sdm845_pdc_regmap_config could
  be used directly
- .resets is used in _(de)assert(), sdm845_pdc_resets could be used
  directly
- .num_resets is only accessed in _probe(),
  ARRAY_SIZE(sdm845_pdc_resets) could be used instead

It probably makes sense if it is planned to support reset controllers
of other SoCs with this driver.

> +struct qcom_pdc_reset_data {
> +	struct reset_controller_dev rcdev;
> +	struct regmap *regmap;
> +	const struct qcom_pdc_desc *desc;
> +};
> +
> +static const struct regmap_config sdm845_pdc_regmap_config = {
> +	.name		= "pdc-reset",
> +	.reg_bits	= 32,
> +	.reg_stride	= 4,
> +	.val_bits	= 32,
> +	.max_register	= 0x20000,
> +	.fast_io	= true,
> +};
> +
> +static const struct qcom_pdc_reset_map sdm845_pdc_resets[] = {
> +	[PDC_APPS_SYNC_RESET] = {0},
> +	[PDC_SP_SYNC_RESET] = {1},
> +	[PDC_AUDIO_SYNC_RESET] = {2},
> +	[PDC_SENSORS_SYNC_RESET] = {3},
> +	[PDC_AOP_SYNC_RESET] = {4},
> +	[PDC_DEBUG_SYNC_RESET] = {5},
> +	[PDC_GPU_SYNC_RESET] = {6},
> +	[PDC_DISPLAY_SYNC_RESET] = {7},
> +	[PDC_COMPUTE_SYNC_RESET] = {8},
> +	[PDC_MODEM_SYNC_RESET] = {9},
> +};
> +
> +static const struct qcom_pdc_desc sdm845_pdc_desc = {
> +	.config = &sdm845_pdc_regmap_config,
> +	.resets = sdm845_pdc_resets,
> +	.num_resets = ARRAY_SIZE(sdm845_pdc_resets),
> +};
> +
> +static inline struct qcom_pdc_reset_data *to_qcom_pdc_reset_data(
> +				struct reset_controller_dev *rcdev)
> +{
> +	return container_of(rcdev, struct qcom_pdc_reset_data, rcdev);
> +}
> +
> +static int qcom_pdc_control_assert(struct reset_controller_dev *rcdev,
> +					unsigned long idx)
> +{
> +	struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev);
> +	const struct qcom_pdc_reset_map *map = &data->desc->resets[idx];
> +
> +	return regmap_update_bits(data->regmap, RPMH_PDC_SYNC_RESET,
> +					BIT(map->bit), BIT(map->bit));
> +}
> +
> +static int qcom_pdc_control_deassert(struct reset_controller_dev *rcdev,
> +					unsigned long idx)
> +{
> +	struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev);
> +	const struct qcom_pdc_reset_map *map = &data->desc->resets[idx];
> +
> +	return regmap_update_bits(data->regmap, RPMH_PDC_SYNC_RESET,
> +					BIT(map->bit), 0);
> +}
> +
> +static const struct reset_control_ops qcom_pdc_reset_ops = {
> +	.assert = qcom_pdc_control_assert,
> +	.deassert = qcom_pdc_control_deassert,
> +};
> +
> +static int qcom_pdc_reset_probe(struct platform_device *pdev)
> +{
> +	struct qcom_pdc_reset_data *data;
> +	struct device *dev = &pdev->dev;
> +	const struct qcom_pdc_desc *desc;
> +	void __iomem *base;
> +	struct resource *res;
> +
> +	desc = of_device_get_match_data(dev);
> +	if (!desc)
> +		return -EINVAL;
> +
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->desc = desc;
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	data->regmap = devm_regmap_init_mmio(dev, base, desc->config);
> +	if (IS_ERR(data->regmap)) {
> +		dev_err(dev, "Unable to get pdc-global regmap");

Add missing '\n'

Say 'pdc-reset' instead of 'pdc-global'? (see also my other comment
below).

> +		return PTR_ERR(data->regmap);
> +	}
> +
> +	data->rcdev.owner = THIS_MODULE;
> +	data->rcdev.ops = &qcom_pdc_reset_ops;
> +	data->rcdev.nr_resets = desc->num_resets;
> +	data->rcdev.of_node = dev->of_node;
> +
> +	return devm_reset_controller_register(dev, &data->rcdev);
> +}
> +
> +static const struct of_device_id qcom_pdc_reset_of_match[] = {
> +	{ .compatible = "qcom,sdm845-pdc-global", .data = &sdm845_pdc_desc },

Should this be 'qcom,sdm845-pdc-reset' which is more specific than
'global' and in line with the name and purpose of the driver?
Obviously this would require to adjust the bindings doc too.

Cheers

Matthias