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/slab.h>
20 #include <linux/spinlock.h>
21 #include <linux/hwspinlock.h>
22 #include <linux/platform_device.h>
23
24 #include "hwspinlock_internal.h"
25
26 /*
27 * Implementation of STE's HSem protocol 1 without interrutps.
28 * The only masterID we allow is '0x01' to force people to use
29 * HSems for synchronisation between processors rather than processes
30 * on the ARM core.
31 */
32
33 #define U8500_MAX_SEMAPHORE 32 /* a total of 32 semaphore */
34 #define RESET_SEMAPHORE (0) /* free */
35
36 /*
37 * CPU ID for master running u8500 kernel.
38 * Hswpinlocks should only be used to synchonise operations
39 * between the Cortex A9 core and the other CPUs. Hence
40 * forcing the masterID to a preset value.
41 */
42 #define HSEM_MASTER_ID 0x01
43
44 #define HSEM_REGISTER_OFFSET 0x08
45
46 #define HSEM_CTRL_REG 0x00
47 #define HSEM_ICRALL 0x90
48 #define HSEM_PROTOCOL_1 0x01
49
u8500_hsem_trylock(struct hwspinlock * lock)50 static int u8500_hsem_trylock(struct hwspinlock *lock)
51 {
52 void __iomem *lock_addr = lock->priv;
53
54 writel(HSEM_MASTER_ID, lock_addr);
55
56 /* get only first 4 bit and compare to masterID.
57 * if equal, we have the semaphore, otherwise
58 * someone else has it.
59 */
60 return (HSEM_MASTER_ID == (0x0F & readl(lock_addr)));
61 }
62
u8500_hsem_unlock(struct hwspinlock * lock)63 static void u8500_hsem_unlock(struct hwspinlock *lock)
64 {
65 void __iomem *lock_addr = lock->priv;
66
67 /* release the lock by writing 0 to it */
68 writel(RESET_SEMAPHORE, lock_addr);
69 }
70
71 /*
72 * u8500: what value is recommended here ?
73 */
u8500_hsem_relax(struct hwspinlock * lock)74 static void u8500_hsem_relax(struct hwspinlock *lock)
75 {
76 ndelay(50);
77 }
78
79 static const struct hwspinlock_ops u8500_hwspinlock_ops = {
80 .trylock = u8500_hsem_trylock,
81 .unlock = u8500_hsem_unlock,
82 .relax = u8500_hsem_relax,
83 };
84
u8500_hsem_probe(struct platform_device * pdev)85 static int u8500_hsem_probe(struct platform_device *pdev)
86 {
87 struct hwspinlock_pdata *pdata = pdev->dev.platform_data;
88 struct hwspinlock_device *bank;
89 struct hwspinlock *hwlock;
90 void __iomem *io_base;
91 int i, num_locks = U8500_MAX_SEMAPHORE;
92 ulong val;
93
94 if (!pdata)
95 return -ENODEV;
96
97 io_base = devm_platform_ioremap_resource(pdev, 0);
98 if (IS_ERR(io_base))
99 return PTR_ERR(io_base);
100
101 /* make sure protocol 1 is selected */
102 val = readl(io_base + HSEM_CTRL_REG);
103 writel((val & ~HSEM_PROTOCOL_1), io_base + HSEM_CTRL_REG);
104
105 /* clear all interrupts */
106 writel(0xFFFF, io_base + HSEM_ICRALL);
107
108 bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks),
109 GFP_KERNEL);
110 if (!bank)
111 return -ENOMEM;
112
113 platform_set_drvdata(pdev, bank);
114
115 for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
116 hwlock->priv = io_base + HSEM_REGISTER_OFFSET + sizeof(u32) * i;
117
118 return devm_hwspin_lock_register(&pdev->dev, bank,
119 &u8500_hwspinlock_ops,
120 pdata->base_id, num_locks);
121 }
122
u8500_hsem_remove(struct platform_device * pdev)123 static void u8500_hsem_remove(struct platform_device *pdev)
124 {
125 struct hwspinlock_device *bank = platform_get_drvdata(pdev);
126 void __iomem *io_base = bank->lock[0].priv - HSEM_REGISTER_OFFSET;
127
128 /* clear all interrupts */
129 writel(0xFFFF, io_base + HSEM_ICRALL);
130 }
131
132 static struct platform_driver u8500_hsem_driver = {
133 .probe = u8500_hsem_probe,
134 .remove_new = u8500_hsem_remove,
135 .driver = {
136 .name = "u8500_hsem",
137 },
138 };
139
u8500_hsem_init(void)140 static int __init u8500_hsem_init(void)
141 {
142 return platform_driver_register(&u8500_hsem_driver);
143 }
144 /* board init code might need to reserve hwspinlocks for predefined purposes */
145 postcore_initcall(u8500_hsem_init);
146
u8500_hsem_exit(void)147 static void __exit u8500_hsem_exit(void)
148 {
149 platform_driver_unregister(&u8500_hsem_driver);
150 }
151 module_exit(u8500_hsem_exit);
152
153 MODULE_LICENSE("GPL v2");
154 MODULE_DESCRIPTION("Hardware Spinlock driver for u8500");
155 MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");
156