tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Atmel SSC driver
3 *
4 * Copyright (C) 2007 Atmel Corporation
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/platform_device.h>
12#include <linux/list.h>
13#include <linux/clk.h>
14#include <linux/err.h>
15#include <linux/io.h>
16#include <linux/spinlock.h>
17#include <linux/atmel-ssc.h>
18
19/* Serialize access to ssc_list and user count */
20static DEFINE_SPINLOCK(user_lock);
21static LIST_HEAD(ssc_list);
22
23struct ssc_device *ssc_request(unsigned int ssc_num)
24{
25 int ssc_valid = 0;
26 struct ssc_device *ssc;
27
28 spin_lock(&user_lock);
29 list_for_each_entry(ssc, &ssc_list, list) {
30 if (ssc->pdev->id == ssc_num) {
31 ssc_valid = 1;
32 break;
33 }
34 }
35
36 if (!ssc_valid) {
37 spin_unlock(&user_lock);
38 pr_err("ssc: ssc%d platform device is missing\n", ssc_num);
39 return ERR_PTR(-ENODEV);
40 }
41
42 if (ssc->user) {
43 spin_unlock(&user_lock);
44 dev_dbg(&ssc->pdev->dev, "module busy\n");
45 return ERR_PTR(-EBUSY);
46 }
47 ssc->user++;
48 spin_unlock(&user_lock);
49
50 clk_enable(ssc->clk);
51
52 return ssc;
53}
54EXPORT_SYMBOL(ssc_request);
55
56void ssc_free(struct ssc_device *ssc)
57{
58 spin_lock(&user_lock);
59 if (ssc->user) {
60 ssc->user--;
61 clk_disable(ssc->clk);
62 } else {
63 dev_dbg(&ssc->pdev->dev, "device already free\n");
64 }
65 spin_unlock(&user_lock);
66}
67EXPORT_SYMBOL(ssc_free);
68
69static int __init ssc_probe(struct platform_device *pdev)
70{
71 int retval = 0;
72 struct resource *regs;
73 struct ssc_device *ssc;
74
75 ssc = kzalloc(sizeof(struct ssc_device), GFP_KERNEL);
76 if (!ssc) {
77 dev_dbg(&pdev->dev, "out of memory\n");
78 retval = -ENOMEM;
79 goto out;
80 }
81
82 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
83 if (!regs) {
84 dev_dbg(&pdev->dev, "no mmio resource defined\n");
85 retval = -ENXIO;
86 goto out_free;
87 }
88
89 ssc->clk = clk_get(&pdev->dev, "pclk");
90 if (IS_ERR(ssc->clk)) {
91 dev_dbg(&pdev->dev, "no pclk clock defined\n");
92 retval = -ENXIO;
93 goto out_free;
94 }
95
96 ssc->pdev = pdev;
97 ssc->regs = ioremap(regs->start, regs->end - regs->start + 1);
98 if (!ssc->regs) {
99 dev_dbg(&pdev->dev, "ioremap failed\n");
100 retval = -EINVAL;
101 goto out_clk;
102 }
103
104 /* disable all interrupts */
105 clk_enable(ssc->clk);
106 ssc_writel(ssc->regs, IDR, ~0UL);
107 ssc_readl(ssc->regs, SR);
108 clk_disable(ssc->clk);
109
110 ssc->irq = platform_get_irq(pdev, 0);
111 if (!ssc->irq) {
112 dev_dbg(&pdev->dev, "could not get irq\n");
113 retval = -ENXIO;
114 goto out_unmap;
115 }
116
117 spin_lock(&user_lock);
118 list_add_tail(&ssc->list, &ssc_list);
119 spin_unlock(&user_lock);
120
121 platform_set_drvdata(pdev, ssc);
122
123 dev_info(&pdev->dev, "Atmel SSC device at 0x%p (irq %d)\n",
124 ssc->regs, ssc->irq);
125
126 goto out;
127
128out_unmap:
129 iounmap(ssc->regs);
130out_clk:
131 clk_put(ssc->clk);
132out_free:
133 kfree(ssc);
134out:
135 return retval;
136}
137
138static int __devexit ssc_remove(struct platform_device *pdev)
139{
140 struct ssc_device *ssc = platform_get_drvdata(pdev);
141
142 spin_lock(&user_lock);
143 iounmap(ssc->regs);
144 clk_put(ssc->clk);
145 list_del(&ssc->list);
146 kfree(ssc);
147 spin_unlock(&user_lock);
148
149 return 0;
150}
151
152static struct platform_driver ssc_driver = {
153 .remove = __devexit_p(ssc_remove),
154 .driver = {
155 .name = "ssc",
156 .owner = THIS_MODULE,
157 },
158};
159
160static int __init ssc_init(void)
161{
162 return platform_driver_probe(&ssc_driver, ssc_probe);
163}
164module_init(ssc_init);
165
166static void __exit ssc_exit(void)
167{
168 platform_driver_unregister(&ssc_driver);
169}
170module_exit(ssc_exit);
171
172MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
173MODULE_DESCRIPTION("SSC driver for Atmel AVR32 and AT91");
174MODULE_LICENSE("GPL");
175MODULE_ALIAS("platform:ssc");