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 | |
38 | static 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(addr: lock_addr)); |
44 | } |
45 | |
46 | static 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, addr: 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 | */ |
64 | static void omap_hwspinlock_relax(struct hwspinlock *lock) |
65 | { |
66 | ndelay(50); |
67 | } |
68 | |
69 | static const struct hwspinlock_ops omap_hwspinlock_ops = { |
70 | .trylock = omap_hwspinlock_trylock, |
71 | .unlock = omap_hwspinlock_unlock, |
72 | .relax = omap_hwspinlock_relax, |
73 | }; |
74 | |
75 | static int omap_hwspinlock_probe(struct platform_device *pdev) |
76 | { |
77 | struct device_node *node = pdev->dev.of_node; |
78 | struct hwspinlock_device *bank; |
79 | struct hwspinlock *hwlock; |
80 | void __iomem *io_base; |
81 | int num_locks, i, ret; |
82 | /* Only a single hwspinlock block device is supported */ |
83 | int base_id = 0; |
84 | |
85 | if (!node) |
86 | return -ENODEV; |
87 | |
88 | io_base = devm_platform_ioremap_resource(pdev, index: 0); |
89 | if (IS_ERR(ptr: io_base)) |
90 | return PTR_ERR(ptr: io_base); |
91 | |
92 | /* |
93 | * make sure the module is enabled and clocked before reading |
94 | * the module SYSSTATUS register |
95 | */ |
96 | pm_runtime_enable(dev: &pdev->dev); |
97 | ret = pm_runtime_resume_and_get(dev: &pdev->dev); |
98 | if (ret < 0) |
99 | goto runtime_err; |
100 | |
101 | /* Determine number of locks */ |
102 | i = readl(addr: io_base + SYSSTATUS_OFFSET); |
103 | i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET; |
104 | |
105 | /* |
106 | * runtime PM will make sure the clock of this module is |
107 | * enabled again iff at least one lock is requested |
108 | */ |
109 | ret = pm_runtime_put(dev: &pdev->dev); |
110 | if (ret < 0) |
111 | goto runtime_err; |
112 | |
113 | /* one of the four lsb's must be set, and nothing else */ |
114 | if (hweight_long(w: i & 0xf) != 1 || i > 8) { |
115 | ret = -EINVAL; |
116 | goto runtime_err; |
117 | } |
118 | |
119 | num_locks = i * 32; /* actual number of locks in this device */ |
120 | |
121 | bank = devm_kzalloc(dev: &pdev->dev, struct_size(bank, lock, num_locks), |
122 | GFP_KERNEL); |
123 | if (!bank) { |
124 | ret = -ENOMEM; |
125 | goto runtime_err; |
126 | } |
127 | |
128 | platform_set_drvdata(pdev, data: bank); |
129 | |
130 | for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++) |
131 | hwlock->priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i; |
132 | |
133 | ret = hwspin_lock_register(bank, dev: &pdev->dev, ops: &omap_hwspinlock_ops, |
134 | base_id, num_locks); |
135 | if (ret) |
136 | goto runtime_err; |
137 | |
138 | dev_dbg(&pdev->dev, "Registered %d locks with HwSpinlock core\n" , |
139 | num_locks); |
140 | |
141 | return 0; |
142 | |
143 | runtime_err: |
144 | pm_runtime_disable(dev: &pdev->dev); |
145 | return ret; |
146 | } |
147 | |
148 | static void omap_hwspinlock_remove(struct platform_device *pdev) |
149 | { |
150 | struct hwspinlock_device *bank = platform_get_drvdata(pdev); |
151 | int ret; |
152 | |
153 | ret = hwspin_lock_unregister(bank); |
154 | if (ret) { |
155 | dev_err(&pdev->dev, "%s failed: %d\n" , __func__, ret); |
156 | return; |
157 | } |
158 | |
159 | pm_runtime_disable(dev: &pdev->dev); |
160 | } |
161 | |
162 | static const struct of_device_id omap_hwspinlock_of_match[] = { |
163 | { .compatible = "ti,omap4-hwspinlock" , }, |
164 | { .compatible = "ti,am64-hwspinlock" , }, |
165 | { .compatible = "ti,am654-hwspinlock" , }, |
166 | { /* end */ }, |
167 | }; |
168 | MODULE_DEVICE_TABLE(of, omap_hwspinlock_of_match); |
169 | |
170 | static struct platform_driver omap_hwspinlock_driver = { |
171 | .probe = omap_hwspinlock_probe, |
172 | .remove_new = omap_hwspinlock_remove, |
173 | .driver = { |
174 | .name = "omap_hwspinlock" , |
175 | .of_match_table = omap_hwspinlock_of_match, |
176 | }, |
177 | }; |
178 | |
179 | static int __init omap_hwspinlock_init(void) |
180 | { |
181 | return platform_driver_register(&omap_hwspinlock_driver); |
182 | } |
183 | /* board init code might need to reserve hwspinlocks for predefined purposes */ |
184 | postcore_initcall(omap_hwspinlock_init); |
185 | |
186 | static void __exit omap_hwspinlock_exit(void) |
187 | { |
188 | platform_driver_unregister(&omap_hwspinlock_driver); |
189 | } |
190 | module_exit(omap_hwspinlock_exit); |
191 | |
192 | MODULE_LICENSE("GPL v2" ); |
193 | MODULE_DESCRIPTION("Hardware spinlock driver for OMAP" ); |
194 | MODULE_AUTHOR("Simon Que <sque@ti.com>" ); |
195 | MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>" ); |
196 | MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>" ); |
197 | |