omap_hwspinlock.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * OMAP hardware spinlock driver
  4 *
  5 * Copyright (C) 2010-2021 Texas Instruments Incorporated - https://www.ti.com
  6 *
  7 * Contact: Simon Que <sque@ti.com>
  8 *          Hari Kanigeri <h-kanigeri2@ti.com>
  9 *          Ohad Ben-Cohen <ohad@wizery.com>
 10 *          Suman Anna <s-anna@ti.com>
 11 */
 12
 13#include <linux/kernel.h>
 14#include <linux/module.h>
 15#include <linux/device.h>
 16#include <linux/delay.h>
 17#include <linux/io.h>
 18#include <linux/bitops.h>
 19#include <linux/pm_runtime.h>
 20#include <linux/slab.h>
 21#include <linux/spinlock.h>
 22#include <linux/hwspinlock.h>
 23#include <linux/of.h>
 24#include <linux/platform_device.h>
 25
 26#include "hwspinlock_internal.h"
 27
 28/* Spinlock register offsets */
 29#define SYSSTATUS_OFFSET		0x0014
 30#define LOCK_BASE_OFFSET		0x0800
 31
 32#define SPINLOCK_NUMLOCKS_BIT_OFFSET	(24)
 33
 34/* Possible values of SPINLOCK_LOCK_REG */
 35#define SPINLOCK_NOTTAKEN		(0)	/* free */
 36#define SPINLOCK_TAKEN			(1)	/* locked */
 37
 38static int omap_hwspinlock_trylock(struct hwspinlock *lock)
 39{
 40	void __iomem *lock_addr = lock->priv;
 41
 42	/* attempt to acquire the lock by reading its value */
 43	return (SPINLOCK_NOTTAKEN == readl(lock_addr));
 44}
 45
 46static void omap_hwspinlock_unlock(struct hwspinlock *lock)
 47{
 48	void __iomem *lock_addr = lock->priv;
 49
 50	/* release the lock by writing 0 to it */
 51	writel(SPINLOCK_NOTTAKEN, lock_addr);
 52}
 53
 54/*
 55 * relax the OMAP interconnect while spinning on it.
 56 *
 57 * The specs recommended that the retry delay time will be
 58 * just over half of the time that a requester would be
 59 * expected to hold the lock.
 60 *
 61 * The number below is taken from an hardware specs example,
 62 * obviously it is somewhat arbitrary.
 63 */
 64static void omap_hwspinlock_relax(struct hwspinlock *lock)
 65{
 66	ndelay(50);
 67}
 68
 69static const struct hwspinlock_ops omap_hwspinlock_ops = {
 70	.trylock = omap_hwspinlock_trylock,
 71	.unlock = omap_hwspinlock_unlock,
 72	.relax = omap_hwspinlock_relax,
 73};
 74
 75static int omap_hwspinlock_probe(struct platform_device *pdev)
 76{
 77	struct hwspinlock_device *bank;
 78	void __iomem *io_base;
 79	int num_locks, i, ret;
 80	/* Only a single hwspinlock block device is supported */
 81	int base_id = 0;
 82
 83	io_base = devm_platform_ioremap_resource(pdev, 0);
 84	if (IS_ERR(io_base))
 85		return PTR_ERR(io_base);
 86
 87	/*
 88	 * make sure the module is enabled and clocked before reading
 89	 * the module SYSSTATUS register
 90	 */
 91	ret = devm_pm_runtime_enable(&pdev->dev);
 92	if (ret)
 93		return ret;
 94	ret = pm_runtime_resume_and_get(&pdev->dev);
 95	if (ret < 0)
 96		return ret;
 97
 98	/* Determine number of locks */
 99	i = readl(io_base + SYSSTATUS_OFFSET);
100	i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
101
102	/*
103	 * runtime PM will make sure the clock of this module is
104	 * enabled again iff at least one lock is requested
105	 */
106	ret = pm_runtime_put(&pdev->dev);
107	if (ret < 0)
108		return ret;
109
110	/* one of the four lsb's must be set, and nothing else */
111	if (hweight_long(i & 0xf) != 1 || i > 8)
112		return -EINVAL;
113
114	num_locks = i * 32; /* actual number of locks in this device */
115
116	bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks),
117			    GFP_KERNEL);
118	if (!bank)
119		return -ENOMEM;
120
121	for (i = 0; i < num_locks; i++)
122		bank->lock[i].priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
123
124	return devm_hwspin_lock_register(&pdev->dev, bank, &omap_hwspinlock_ops,
125						base_id, num_locks);
126}
127
128static const struct of_device_id omap_hwspinlock_of_match[] = {
129	{ .compatible = "ti,omap4-hwspinlock", },
130	{ .compatible = "ti,am64-hwspinlock", },
131	{ .compatible = "ti,am654-hwspinlock", },
132	{ /* end */ },
133};
134MODULE_DEVICE_TABLE(of, omap_hwspinlock_of_match);
135
136static struct platform_driver omap_hwspinlock_driver = {
137	.probe		= omap_hwspinlock_probe,
138	.driver		= {
139		.name	= "omap_hwspinlock",
140		.of_match_table = omap_hwspinlock_of_match,
141	},
142};
143
144static int __init omap_hwspinlock_init(void)
145{
146	return platform_driver_register(&omap_hwspinlock_driver);
147}
148/* board init code might need to reserve hwspinlocks for predefined purposes */
149postcore_initcall(omap_hwspinlock_init);
150
151static void __exit omap_hwspinlock_exit(void)
152{
153	platform_driver_unregister(&omap_hwspinlock_driver);
154}
155module_exit(omap_hwspinlock_exit);
156
157MODULE_LICENSE("GPL v2");
158MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
159MODULE_AUTHOR("Simon Que <sque@ti.com>");
160MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
161MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");