RE: [PATCH v2 4/5] firmware: arm_scmi: Add RESET protocol in SCMI v2.0

[Peng Fan <peng.fan@nxp.com>]

> Subject: [PATCH v2 4/5] firmware: arm_scmi: Add RESET protocol in SCMI
> v2.0
> 
> SCMIv2.0 adds a new Reset Management Protocol to manage various reset
> states a given device or domain can enter. Device(s) that can be collectively
> reset through a common reset signal constitute a reset domain for the
> firmware.
> 
> A reset domain can be reset autonomously or explicitly through assertion and
> de-assertion of the signal. When autonomous reset is chosen, the firmware is
> responsible for taking the necessary steps to reset the domain and to
> subsequently bring it out of reset. When explicit reset is chosen, the caller has
> to specifically assert and then de-assert the reset signal by issuing two
> separate RESET commands.
> 
> Add the basic SCMI reset infrastructure that can be used by Linux reset
> controller driver.
> 
> Cc: Philipp Zabel <p.zabel@pengutronix.de>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  drivers/firmware/arm_scmi/Makefile |   2 +-
>  drivers/firmware/arm_scmi/reset.c  | 231
> +++++++++++++++++++++++++++++
>  include/linux/scmi_protocol.h      |  26 ++++
>  3 files changed, 258 insertions(+), 1 deletion(-)  create mode 100644
> drivers/firmware/arm_scmi/reset.c
> 
> diff --git a/drivers/firmware/arm_scmi/Makefile
> b/drivers/firmware/arm_scmi/Makefile
> index c47d28d556b6..5f298f00a82e 100644
> --- a/drivers/firmware/arm_scmi/Makefile
> +++ b/drivers/firmware/arm_scmi/Makefile
> @@ -2,5 +2,5 @@
>  obj-y	= scmi-bus.o scmi-driver.o scmi-protocols.o
>  scmi-bus-y = bus.o
>  scmi-driver-y = driver.o
> -scmi-protocols-y = base.o clock.o perf.o power.o sensors.o
> +scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o
>  obj-$(CONFIG_ARM_SCMI_POWER_DOMAIN) += scmi_pm_domain.o diff
> --git a/drivers/firmware/arm_scmi/reset.c
> b/drivers/firmware/arm_scmi/reset.c
> new file mode 100644
> index 000000000000..11cb8b5ccf34
> --- /dev/null
> +++ b/drivers/firmware/arm_scmi/reset.c
> @@ -0,0 +1,231 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * System Control and Management Interface (SCMI) Reset Protocol
> + *
> + * Copyright (C) 2019 ARM Ltd.
> + */
> +
> +#include "common.h"
> +
> +enum scmi_reset_protocol_cmd {
> +	RESET_DOMAIN_ATTRIBUTES = 0x3,
> +	RESET = 0x4,
> +	RESET_NOTIFY = 0x5,
> +};
> +
> +enum scmi_reset_protocol_notify {
> +	RESET_ISSUED = 0x0,
> +};
> +
> +#define NUM_RESET_DOMAIN_MASK	0xffff
> +#define RESET_NOTIFY_ENABLE	BIT(0)
> +
> +struct scmi_msg_resp_reset_domain_attributes {
> +	__le32 attributes;
> +#define SUPPORTS_ASYNC_RESET(x)		((x) & BIT(31))
> +#define SUPPORTS_NOTIFY_RESET(x)	((x) & BIT(30))
> +	__le32 latency;
> +	    u8 name[SCMI_MAX_STR_SIZE];
> +};
> +
> +struct scmi_msg_reset_domain_reset {
> +	__le32 domain_id;
> +	__le32 flags;
> +#define AUTONOMOUS_RESET	BIT(0)
> +#define EXPLICIT_RESET_ASSERT	BIT(1)
> +#define ASYNCHRONOUS_RESET	BIT(2)
> +	__le32 reset_state;
> +#define ARCH_RESET_TYPE		BIT(31)
> +#define COLD_RESET_STATE	BIT(0)
> +#define ARCH_COLD_RESET		(ARCH_RESET_TYPE |
> COLD_RESET_STATE)
> +};
> +
> +struct reset_dom_info {
> +	bool async_reset;
> +	bool reset_notify;
> +	u32 latency_us;
> +	char name[SCMI_MAX_STR_SIZE];
> +};
> +
> +struct scmi_reset_info {
> +	int num_domains;
> +	struct reset_dom_info *dom_info;
> +};
> +
> +static int scmi_reset_attributes_get(const struct scmi_handle *handle,
> +				     struct scmi_reset_info *pi)
> +{
> +	int ret;
> +	struct scmi_xfer *t;
> +	u32 *attr;
> +
> +	ret = scmi_xfer_get_init(handle, PROTOCOL_ATTRIBUTES,
> +				 SCMI_PROTOCOL_RESET, 0, sizeof(*attr), &t);
> +	if (ret)
> +		return ret;
> +
> +	attr = t->rx.buf;
> +
> +	ret = scmi_do_xfer(handle, t);
> +	if (!ret)
> +		pi->num_domains = le32_to_cpu(*attr) &
> NUM_RESET_DOMAIN_MASK;
> +
> +	scmi_xfer_put(handle, t);
> +	return ret;
> +}
> +
> +static int
> +scmi_reset_domain_attributes_get(const struct scmi_handle *handle, u32
> domain,
> +				 struct reset_dom_info *dom_info)
> +{
> +	int ret;
> +	struct scmi_xfer *t;
> +	struct scmi_msg_resp_reset_domain_attributes *attr;
> +
> +	ret = scmi_xfer_get_init(handle, RESET_DOMAIN_ATTRIBUTES,
> +				 SCMI_PROTOCOL_RESET, sizeof(domain),
> +				 sizeof(*attr), &t);
> +	if (ret)
> +		return ret;
> +
> +	*(__le32 *)t->tx.buf = cpu_to_le32(domain);
> +	attr = t->rx.buf;
> +
> +	ret = scmi_do_xfer(handle, t);
> +	if (!ret) {
> +		u32 attributes = le32_to_cpu(attr->attributes);
> +
> +		dom_info->async_reset = SUPPORTS_ASYNC_RESET(attributes);
> +		dom_info->reset_notify = SUPPORTS_NOTIFY_RESET(attributes);
> +		dom_info->latency_us = le32_to_cpu(attr->latency);
> +		if (dom_info->latency_us == U32_MAX)
> +			dom_info->latency_us = 0;
> +		strlcpy(dom_info->name, attr->name, SCMI_MAX_STR_SIZE);
> +	}
> +
> +	scmi_xfer_put(handle, t);
> +	return ret;
> +}
> +
> +static int scmi_reset_num_domains_get(const struct scmi_handle *handle)
> +{
> +	struct scmi_reset_info *pi = handle->reset_priv;
> +
> +	return pi->num_domains;
> +}
> +
> +static char *scmi_reset_name_get(const struct scmi_handle *handle, u32
> +domain) {
> +	struct scmi_reset_info *pi = handle->reset_priv;
> +	struct reset_dom_info *dom = pi->dom_info + domain;
> +
> +	return dom->name;
> +}
> +
> +static int scmi_reset_latency_get(const struct scmi_handle *handle, u32
> +domain) {
> +	struct scmi_reset_info *pi = handle->reset_priv;
> +	struct reset_dom_info *dom = pi->dom_info + domain;
> +
> +	return dom->latency_us;
> +}
> +
> +static int scmi_domain_reset(const struct scmi_handle *handle, u32 domain,
> +			     u32 flags, u32 state)
> +{
> +	int ret;
> +	struct scmi_xfer *t;
> +	struct scmi_msg_reset_domain_reset *dom;
> +	struct scmi_reset_info *pi = handle->reset_priv;
> +	struct reset_dom_info *rdom = pi->dom_info + domain;
> +
> +	if (rdom->async_reset)
> +		flags |= ASYNCHRONOUS_RESET;
> +
> +	ret = scmi_xfer_get_init(handle, RESET, SCMI_PROTOCOL_RESET,
> +				 sizeof(*dom), 0, &t);
> +	if (ret)
> +		return ret;
> +
> +	dom = t->tx.buf;
> +	dom->domain_id = cpu_to_le32(domain);
> +	dom->flags = cpu_to_le32(flags);
> +	dom->domain_id = cpu_to_le32(state);
> +
> +	if (rdom->async_reset)
> +		ret = scmi_do_xfer_with_response(handle, t);
> +	else
> +		ret = scmi_do_xfer(handle, t);
> +
> +	scmi_xfer_put(handle, t);
> +	return ret;
> +}
> +
> +static int scmi_reset_domain_reset(const struct scmi_handle *handle,
> +u32 domain) {
> +	return scmi_domain_reset(handle, domain, AUTONOMOUS_RESET,
> +				 ARCH_COLD_RESET);
> +}
> +
> +static int
> +scmi_reset_domain_assert(const struct scmi_handle *handle, u32 domain)
> +{
> +	return scmi_domain_reset(handle, domain, EXPLICIT_RESET_ASSERT,
> +				 ARCH_COLD_RESET);
> +}
> +
> +static int
> +scmi_reset_domain_deassert(const struct scmi_handle *handle, u32
> +domain) {
> +	return scmi_domain_reset(handle, domain, 0, ARCH_COLD_RESET); }
> +
> +static struct scmi_reset_ops reset_ops = {
> +	.num_domains_get = scmi_reset_num_domains_get,
> +	.name_get = scmi_reset_name_get,
> +	.latency_get = scmi_reset_latency_get,
> +	.reset = scmi_reset_domain_reset,
> +	.assert = scmi_reset_domain_assert,
> +	.deassert = scmi_reset_domain_deassert, };
> +
> +static int scmi_reset_protocol_init(struct scmi_handle *handle) {
> +	int domain;
> +	u32 version;
> +	struct scmi_reset_info *pinfo;
> +
> +	scmi_version_get(handle, SCMI_PROTOCOL_RESET, &version);
> +
> +	dev_dbg(handle->dev, "Reset Version %d.%d\n",
> +		PROTOCOL_REV_MAJOR(version),
> PROTOCOL_REV_MINOR(version));
> +
> +	pinfo = devm_kzalloc(handle->dev, sizeof(*pinfo), GFP_KERNEL);
> +	if (!pinfo)
> +		return -ENOMEM;
> +
> +	scmi_reset_attributes_get(handle, pinfo);
> +
> +	pinfo->dom_info = devm_kcalloc(handle->dev, pinfo->num_domains,
> +				       sizeof(*pinfo->dom_info), GFP_KERNEL);
> +	if (!pinfo->dom_info)
> +		return -ENOMEM;
> +
> +	for (domain = 0; domain < pinfo->num_domains; domain++) {
> +		struct reset_dom_info *dom = pinfo->dom_info + domain;
> +
> +		scmi_reset_domain_attributes_get(handle, domain, dom);
> +	}
> +
> +	handle->reset_ops = &reset_ops;
> +	handle->reset_priv = pinfo;
> +
> +	return 0;
> +}
> +
> +static int __init scmi_reset_init(void) {
> +	return scmi_protocol_register(SCMI_PROTOCOL_RESET,
> +				      &scmi_reset_protocol_init);
> +}
> +subsys_initcall(scmi_reset_init);
> diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> index f0f2b53a1dac..881fea47c83d 100644
> --- a/include/linux/scmi_protocol.h
> +++ b/include/linux/scmi_protocol.h
> @@ -187,6 +187,26 @@ struct scmi_sensor_ops {
>  			   u64 *value);
>  };
> 
> +/**
> + * struct scmi_reset_ops - represents the various operations provided
> + *	by SCMI Reset Protocol
> + *
> + * @num_domains_get: get the count of reset domains provided by SCMI
> + * @name_get: gets the name of a reset domain
> + * @latency_get: gets the reset latency for the specified reset domain
> + * @reset: resets the specified reset domain
> + * @assert: explicitly assert reset signal of the specified reset
> +domain
> + * @deassert: explicitly deassert reset signal of the specified reset
> +domain  */ struct scmi_reset_ops {
> +	int (*num_domains_get)(const struct scmi_handle *handle);
> +	char *(*name_get)(const struct scmi_handle *handle, u32 domain);
> +	int (*latency_get)(const struct scmi_handle *handle, u32 domain);
> +	int (*reset)(const struct scmi_handle *handle, u32 domain);
> +	int (*assert)(const struct scmi_handle *handle, u32 domain);
> +	int (*deassert)(const struct scmi_handle *handle, u32 domain); };
> +
>  /**
>   * struct scmi_handle - Handle returned to ARM SCMI clients for usage.
>   *
> @@ -196,6 +216,7 @@ struct scmi_sensor_ops {
>   * @perf_ops: pointer to set of performance protocol operations
>   * @clk_ops: pointer to set of clock protocol operations
>   * @sensor_ops: pointer to set of sensor protocol operations
> + * @reset_ops: pointer to set of reset protocol operations
>   * @perf_priv: pointer to private data structure specific to performance
>   *	protocol(for internal use only)
>   * @clk_priv: pointer to private data structure specific to clock @@ -204,6
> +225,8 @@ struct scmi_sensor_ops {
>   *	protocol(for internal use only)
>   * @sensor_priv: pointer to private data structure specific to sensors
>   *	protocol(for internal use only)
> + * @reset_priv: pointer to private data structure specific to reset
> + *	protocol(for internal use only)
>   */
>  struct scmi_handle {
>  	struct device *dev;
> @@ -212,11 +235,13 @@ struct scmi_handle {
>  	struct scmi_clk_ops *clk_ops;
>  	struct scmi_power_ops *power_ops;
>  	struct scmi_sensor_ops *sensor_ops;
> +	struct scmi_reset_ops *reset_ops;
>  	/* for protocol internal use */
>  	void *perf_priv;
>  	void *clk_priv;
>  	void *power_priv;
>  	void *sensor_priv;
> +	void *reset_priv;
>  };
> 
>  enum scmi_std_protocol {
> @@ -226,6 +251,7 @@ enum scmi_std_protocol {
>  	SCMI_PROTOCOL_PERF = 0x13,
>  	SCMI_PROTOCOL_CLOCK = 0x14,
>  	SCMI_PROTOCOL_SENSOR = 0x15,
> +	SCMI_PROTOCOL_RESET = 0x16,
>  };

Reviewed-by: Peng Fan <peng.fan@nxp.com>

> 
>  struct scmi_device {
> --
> 2.17.1


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