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	devm_pm_runtime_enable(&pdev->dev);
92	ret = pm_runtime_resume_and_get(&pdev->dev);
93	if (ret < 0)
94		return ret;
95
96	/* Determine number of locks */
97	i = readl(io_base + SYSSTATUS_OFFSET);
98	i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
99
100	/*
101	 * runtime PM will make sure the clock of this module is
102	 * enabled again iff at least one lock is requested
103	 */
104	ret = pm_runtime_put(&pdev->dev);
105	if (ret < 0)
106		return ret;
107
108	/* one of the four lsb's must be set, and nothing else */
109	if (hweight_long(i & 0xf) != 1 || i > 8)
110		return -EINVAL;
111
112	num_locks = i * 32; /* actual number of locks in this device */
113
114	bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks),
115			    GFP_KERNEL);
116	if (!bank)
117		return -ENOMEM;
118
119	for (i = 0; i < num_locks; i++)
120		bank->lock[i].priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
121
122	return devm_hwspin_lock_register(&pdev->dev, bank, &omap_hwspinlock_ops,
123						base_id, num_locks);
124}
125
126static const struct of_device_id omap_hwspinlock_of_match[] = {
127	{ .compatible = "ti,omap4-hwspinlock", },
128	{ .compatible = "ti,am64-hwspinlock", },
129	{ .compatible = "ti,am654-hwspinlock", },
130	{ /* end */ },
131};
132MODULE_DEVICE_TABLE(of, omap_hwspinlock_of_match);
133
134static struct platform_driver omap_hwspinlock_driver = {
135	.probe		= omap_hwspinlock_probe,
136	.driver		= {
137		.name	= "omap_hwspinlock",
138		.of_match_table = omap_hwspinlock_of_match,
139	},
140};
141
142static int __init omap_hwspinlock_init(void)
143{
144	return platform_driver_register(&omap_hwspinlock_driver);
145}
146/* board init code might need to reserve hwspinlocks for predefined purposes */
147postcore_initcall(omap_hwspinlock_init);
148
149static void __exit omap_hwspinlock_exit(void)
150{
151	platform_driver_unregister(&omap_hwspinlock_driver);
152}
153module_exit(omap_hwspinlock_exit);
154
155MODULE_LICENSE("GPL v2");
156MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
157MODULE_AUTHOR("Simon Que <sque@ti.com>");
158MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
159MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
160