soc: qcom: Add RPM SMD Driver

Introduction

============

Resource Power Manager (RPM)

RPM is a dedicated hardware engine for managing shared SoC resources,

which includes buses, clocks, power rails, etc.  The goal of RPM is

to achieve the maximum power savings while satisfying the SoC's

operational and performance requirements.  RPM accepts resource

requests from multiple RPM masters.  It arbitrates and aggregates the

requests, and configures the shared resources.  The RPM masters are

the application processor, the modem processor, as well as some

hardware accelerators.

The RPM driver provides an API for interacting with RPM.  Kernel code

calls the RPM driver to request RPM-managed, shared resources.

Kernel code can also register with the driver for RPM notifications,

which are sent when the status of shared resources change.

Hardware description

====================

RPM exposes a separate region of registers to each of the RPM masters.

In general, each register represents some shared resource(s).  At a

very basic level, a master requests resources by writing to the

registers, then generating an interrupt to RPM.  RPM processes the

request, writes acknowledgment to the registers, then generates an

interrupt to the master.

In addition to the master-specific regions, RPM also exposes a shared

region that contains the current status of the shared resources.  Only

RPM can write to the status region, but every master can read from it.

RPM contains internal logics that aggregate and arbitrate among

requests from the various RPM masters.  It interfaces with the PMIC,

the bus arbitration block, and the clock controller block in order to

configure the shared resources.

Software description

====================

The RPM driver encapsulates the low level RPM interactions, which

rely on reading/writing registers and generating/processing

interrupts, and provides a higher level synchronuous set/clear/get

interface.  Most functions take an array of id-value pairs.

The ids identify the RPM registers which would correspond to some

RPM resources, the values specify the new resource values.

The RPM driver synchronizes accesses to RPM.  It protects against

simultaneous accesses from multiple tasks, on SMP cores, in task

contexts, and in atomic contexts.

Design

======

Design goals:

- Encapsulate low level RPM interactions.

- Provide a synchronuous set/clear/get interface.

- Synchronize simultaneous software accesses to RPM.

Power Management

================

RPM is part of the power management architecture for MSM 8660.  RPM

manages shared system resources to lower system power.

SMP/multi-core

==============

The RPM driver uses mutex to synchronize client accesses among tasks.

It uses spinlocks to synchronize accesses from atomic contexts and

SMP cores.

Security

========

None.

Performance

===========

None.

Interface

=========

msm_rpm_get_status():

The function reads the shared status region and returns the current

resource values, which are the arbitrated/aggregated results across

all RPM masters.

msm_rpm_set():

The function makes a resource request to RPM.

msm_rpm_set_noirq():

The function is similar to msm_rpm_set() except that it must be

called with interrupts masked.  If possible, use msm_rpm_set()

instead, to maximize CPU throughput.

msm_rpm_clear():

The function makes a resource request to RPM to clear resource values.

Once the values are cleared, the resources revert back to their default

values for this RPM master.  RPM internally uses the default values as

the requests from this RPM master when arbitrating and aggregating with

requests from other RPM masters.

msm_rpm_clear_noirq():

The function is similar to msm_rpm_clear() except that it must be

called with interrupts masked.  If possible, use msm_rpm_clear()

instead, to maximize CPU throughput.

msm_rpm_register_notification():

The function registers for RPM notification.  When the specified

resources change their status on RPM, RPM sends out notifications

and the driver will "up" the semaphore in struct

msm_rpm_notification.

msm_rpm_unregister_notification():

The function unregisters a notification.

msm_rpm_init():

The function initializes the RPM driver with platform specific data.

Driver parameters

=================

None.

Config options

==============

MSM_RPM

Dependencies

============

None.

User space utilities

====================

None.

Other

=====

None.

Known issues

============

None.

To do

=====

None.

Resource Power Manager(RPM)

RPM is a dedicated hardware engine for managing shared SoC resources,

which includes buses, clocks, power rails, etc.  The goal of RPM is

to achieve the maximum power savings while satisfying the SoC's

operational and performance requirements.  RPM accepts resource

requests from multiple RPM masters.  It arbitrates and aggregates the

requests, and configures the shared resources.  The RPM masters are

the application processor, the modem processor, as well as hardware

accelerators. The RPM driver communicates with the hardware engine using

SMD.

The devicetree representation of the SPM block should be:

Required properties

- compatible: "qcom,rpm-smd" or "qcom,rpm-glink"

- rpm-channel-name: The string corresponding to the channel name of the

			peripheral subsystem. Required for both smd and

			glink transports.

- rpm-channel-type: The interal SMD edge for this subsystem found in

			<soc/qcom/smd.h>

- qcom,glink-edge: Logical name of the remote subsystem. This is a required

			property when rpm-smd driver using glink as trasport.

Optional properties

- rpm-standalone: Allow RPM driver to run in standalone mode irrespective of RPM

			channel presence.

- reg: Contains the memory address at which rpm messaging format version is

  stored. If this field is not present, the target only supports v0 format.

Example:

	qcom,rpm-smd@68150 {

		compatible = "qcom,rpm-smd", "qcom,rpm-glink";

		reg = <0x68150 0x3200>;

		qcom,rpm-channel-name = "rpm_requests";

		qcom,rpm-channel-type = 15; /* SMD_APPS_RPM */

		qcom,glink-edge = "rpm";

	}

}

	help

	  This defines maximum number of entries to be allocated for application

	  subsytem in Minidump table.

config MSM_RPM_SMD

	bool "RPM driver using SMD protocol"

	help

	  RPM is the dedicated hardware engine for managing shared SoC

	  resources. This config adds driver support for using SMD as a

	  transport layer communication with RPM hardware. It also selects

	  the MSM_MPM config that programs the MPM module to monitor interrupts

	  during sleep modes.

config QCOM_BUS_SCALING

	bool "Bus scaling driver"

endif

obj-$(CONFIG_QMP_DEBUGFS_CLIENT) += qmp-debugfs-client.o

obj-$(CONFIG_MSM_PERFORMANCE) += msm_performance.o

obj-$(CONFIG_MSM_RPM_SMD)   +=  rpm-smd.o

ifdef CONFIG_DEBUG_FS

obj-$(CONFIG_MSM_RPM_SMD)   +=  rpm-smd-debug.o

endif

/* Copyright (c) 2013-2014, 2017,  The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only version 2 as published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 */

#define pr_fmt(fmt) "rpm-smd-debug: %s(): " fmt, __func__

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/debugfs.h>

#include <linux/list.h>

#include <linux/io.h>

#include <linux/uaccess.h>

#include <linux/slab.h>

#include <soc/qcom/rpm-smd.h>

#define MAX_MSG_BUFFER 350

#define MAX_KEY_VALUE_PAIRS 20

static struct dentry *rpm_debugfs_dir;

static u32 string_to_uint(const u8 *str)

{

	int i, len;

	u32 output = 0;

	len = strnlen(str, sizeof(u32));

	for (i = 0; i < len; i++)

		output |= str[i] << (i * 8);

	return output;

}

static ssize_t rsc_ops_write(struct file *fp, const char __user *user_buffer,

						size_t count, loff_t *position)

{

	char buf[MAX_MSG_BUFFER], rsc_type_str[6] = {}, rpm_set[8] = {},

						key_str[6] = {};

	int i, pos = -1, set = -1, nelems = -1;

	char *cmp;

	uint32_t rsc_type = 0, rsc_id = 0, key = 0, data = 0;

	struct msm_rpm_request *req;

	count = min(count, sizeof(buf) - 1);

	if (copy_from_user(&buf, user_buffer, count))

		return -EFAULT;

	buf[count] = '\0';

	cmp = strstrip(buf);

	if (sscanf(cmp, "%7s %5s %u %d %n", rpm_set, rsc_type_str,

				&rsc_id, &nelems, &pos) != 4) {

		pr_err("Invalid number of arguments passed\n");

		goto err;

	}

	if (strlen(rpm_set) > 6 || strlen(rsc_type_str) > 4) {

		pr_err("Invalid value of set or resource type\n");

		goto err;

	}

	if (!strcmp(rpm_set, "active"))

		set = 0;

	else if (!strcmp(rpm_set, "sleep"))

		set = 1;

	rsc_type = string_to_uint(rsc_type_str);

	if (set < 0 || nelems < 0) {

		pr_err("Invalid value of set or nelems\n");

		goto err;

	}

	if (nelems > MAX_KEY_VALUE_PAIRS) {

		pr_err("Exceeded max no of key-value entries\n");

		goto err;

	}

	req = msm_rpm_create_request(set, rsc_type, rsc_id, nelems);

	if (!req)

		return -ENOMEM;

	for (i = 0; i < nelems; i++) {

		cmp += pos;

		if (sscanf(cmp, "%5s %n", key_str, &pos) != 1) {

			pr_err("Invalid number of arguments passed\n");

			goto err;

		}

		if (strlen(key_str) > 4) {

			pr_err("Key value cannot be more than 4 charecters");

			goto err;

		}

		key = string_to_uint(key_str);

		if (!key) {

			pr_err("Key values entered incorrectly\n");

			goto err;

		}

		cmp += pos;

		if (sscanf(cmp, "%u %n", &data, &pos) != 1) {

			pr_err("Invalid number of arguments passed\n");

			goto err;

		}

		if (msm_rpm_add_kvp_data(req, key,

				(void *)&data, sizeof(data)))

			goto err_request;

	}

	if (msm_rpm_wait_for_ack(msm_rpm_send_request(req)))

		pr_err("Sending the RPM message failed\n");

err_request:

	msm_rpm_free_request(req);

err:

	return count;

}

static const struct file_operations rsc_ops = {

	.write = rsc_ops_write,

};

static int __init rpm_smd_debugfs_init(void)

{

	rpm_debugfs_dir = debugfs_create_dir("rpm_send_msg", NULL);

	if (!rpm_debugfs_dir)

		return -ENOMEM;

	if (!debugfs_create_file("message", 0200, rpm_debugfs_dir, NULL,

								&rsc_ops))

		return -ENOMEM;

	return 0;

}

late_initcall(rpm_smd_debugfs_init);

static void __exit rpm_smd_debugfs_exit(void)

{

	debugfs_remove_recursive(rpm_debugfs_dir);

}

module_exit(rpm_smd_debugfs_exit);

MODULE_DESCRIPTION("RPM SMD Debug Driver");

MODULE_LICENSE("GPL v2");