GNU Linux-libre 5.10.219-gnu1
[releases.git] / drivers / hwspinlock / u8500_hsem.c
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
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
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  */
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
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
123 static int 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         return 0;
132 }
133
134 static struct platform_driver u8500_hsem_driver = {
135         .probe          = u8500_hsem_probe,
136         .remove         = u8500_hsem_remove,
137         .driver         = {
138                 .name   = "u8500_hsem",
139         },
140 };
141
142 static int __init u8500_hsem_init(void)
143 {
144         return platform_driver_register(&u8500_hsem_driver);
145 }
146 /* board init code might need to reserve hwspinlocks for predefined purposes */
147 postcore_initcall(u8500_hsem_init);
148
149 static void __exit u8500_hsem_exit(void)
150 {
151         platform_driver_unregister(&u8500_hsem_driver);
152 }
153 module_exit(u8500_hsem_exit);
154
155 MODULE_LICENSE("GPL v2");
156 MODULE_DESCRIPTION("Hardware Spinlock driver for u8500");
157 MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");