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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * u8500 HWSEM driver
4 *
5 * Copyright (C) 2010-2011 ST-Ericsson
6 *
7 * Implements u8500 semaphore handling for protocol 1, no interrupts.
8 *
9 * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
10 * Heavily borrowed from the work of :
11 * Simon Que <sque@ti.com>
12 * Hari Kanigeri <h-kanigeri2@ti.com>
13 * Ohad Ben-Cohen <ohad@wizery.com>
14 */
15
16#include <linux/module.h>
17#include <linux/delay.h>
18#include <linux/io.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/platform_device.h>
24
25#include "hwspinlock_internal.h"
26
27/*
28 * Implementation of STE's HSem protocol 1 without interrutps.
29 * The only masterID we allow is '0x01' to force people to use
30 * HSems for synchronisation between processors rather than processes
31 * on the ARM core.
32 */
33
34#define U8500_MAX_SEMAPHORE 32 /* a total of 32 semaphore */
35#define RESET_SEMAPHORE (0) /* free */
36
37/*
38 * CPU ID for master running u8500 kernel.
39 * Hswpinlocks should only be used to synchonise operations
40 * between the Cortex A9 core and the other CPUs. Hence
41 * forcing the masterID to a preset value.
42 */
43#define HSEM_MASTER_ID 0x01
44
45#define HSEM_REGISTER_OFFSET 0x08
46
47#define HSEM_CTRL_REG 0x00
48#define HSEM_ICRALL 0x90
49#define HSEM_PROTOCOL_1 0x01
50
51static int u8500_hsem_trylock(struct hwspinlock *lock)
52{
53 void __iomem *lock_addr = lock->priv;
54
55 writel(HSEM_MASTER_ID, lock_addr);
56
57 /* get only first 4 bit and compare to masterID.
58 * if equal, we have the semaphore, otherwise
59 * someone else has it.
60 */
61 return (HSEM_MASTER_ID == (0x0F & readl(lock_addr)));
62}
63
64static void u8500_hsem_unlock(struct hwspinlock *lock)
65{
66 void __iomem *lock_addr = lock->priv;
67
68 /* release the lock by writing 0 to it */
69 writel(RESET_SEMAPHORE, lock_addr);
70}
71
72/*
73 * u8500: what value is recommended here ?
74 */
75static void u8500_hsem_relax(struct hwspinlock *lock)
76{
77 ndelay(50);
78}
79
80static const struct hwspinlock_ops u8500_hwspinlock_ops = {
81 .trylock = u8500_hsem_trylock,
82 .unlock = u8500_hsem_unlock,
83 .relax = u8500_hsem_relax,
84};
85
86static int u8500_hsem_probe(struct platform_device *pdev)
87{
88 struct hwspinlock_pdata *pdata = pdev->dev.platform_data;
89 struct hwspinlock_device *bank;
90 struct hwspinlock *hwlock;
91 struct resource *res;
92 void __iomem *io_base;
93 int i, ret, num_locks = U8500_MAX_SEMAPHORE;
94 ulong val;
95
96 if (!pdata)
97 return -ENODEV;
98
99 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
100 if (!res)
101 return -ENODEV;
102
103 io_base = ioremap(res->start, resource_size(res));
104 if (!io_base)
105 return -ENOMEM;
106
107 /* make sure protocol 1 is selected */
108 val = readl(io_base + HSEM_CTRL_REG);
109 writel((val & ~HSEM_PROTOCOL_1), io_base + HSEM_CTRL_REG);
110
111 /* clear all interrupts */
112 writel(0xFFFF, io_base + HSEM_ICRALL);
113
114 bank = kzalloc(struct_size(bank, lock, num_locks), GFP_KERNEL);
115 if (!bank) {
116 ret = -ENOMEM;
117 goto iounmap_base;
118 }
119
120 platform_set_drvdata(pdev, bank);
121
122 for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
123 hwlock->priv = io_base + HSEM_REGISTER_OFFSET + sizeof(u32) * i;
124
125 /* no pm needed for HSem but required to comply with hwspilock core */
126 pm_runtime_enable(&pdev->dev);
127
128 ret = hwspin_lock_register(bank, &pdev->dev, &u8500_hwspinlock_ops,
129 pdata->base_id, num_locks);
130 if (ret)
131 goto reg_fail;
132
133 return 0;
134
135reg_fail:
136 pm_runtime_disable(&pdev->dev);
137 kfree(bank);
138iounmap_base:
139 iounmap(io_base);
140 return ret;
141}
142
143static int u8500_hsem_remove(struct platform_device *pdev)
144{
145 struct hwspinlock_device *bank = platform_get_drvdata(pdev);
146 void __iomem *io_base = bank->lock[0].priv - HSEM_REGISTER_OFFSET;
147 int ret;
148
149 /* clear all interrupts */
150 writel(0xFFFF, io_base + HSEM_ICRALL);
151
152 ret = hwspin_lock_unregister(bank);
153 if (ret) {
154 dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
155 return ret;
156 }
157
158 pm_runtime_disable(&pdev->dev);
159 iounmap(io_base);
160 kfree(bank);
161
162 return 0;
163}
164
165static struct platform_driver u8500_hsem_driver = {
166 .probe = u8500_hsem_probe,
167 .remove = u8500_hsem_remove,
168 .driver = {
169 .name = "u8500_hsem",
170 },
171};
172
173static int __init u8500_hsem_init(void)
174{
175 return platform_driver_register(&u8500_hsem_driver);
176}
177/* board init code might need to reserve hwspinlocks for predefined purposes */
178postcore_initcall(u8500_hsem_init);
179
180static void __exit u8500_hsem_exit(void)
181{
182 platform_driver_unregister(&u8500_hsem_driver);
183}
184module_exit(u8500_hsem_exit);
185
186MODULE_LICENSE("GPL v2");
187MODULE_DESCRIPTION("Hardware Spinlock driver for u8500");
188MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");