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 #include <linux/slab.h>
19 #include <linux/module.h>
20
21 /* Serialize access to ssc_list and user count */
22 static DEFINE_SPINLOCK(user_lock);
23 static LIST_HEAD(ssc_list);
24
ssc_request(unsigned int ssc_num)25 struct ssc_device *ssc_request(unsigned int ssc_num)
26 {
27 int ssc_valid = 0;
28 struct ssc_device *ssc;
29
30 spin_lock(&user_lock);
31 list_for_each_entry(ssc, &ssc_list, list) {
32 if (ssc->pdev->id == ssc_num) {
33 ssc_valid = 1;
34 break;
35 }
36 }
37
38 if (!ssc_valid) {
39 spin_unlock(&user_lock);
40 pr_err("ssc: ssc%d platform device is missing\n", ssc_num);
41 return ERR_PTR(-ENODEV);
42 }
43
44 if (ssc->user) {
45 spin_unlock(&user_lock);
46 dev_dbg(&ssc->pdev->dev, "module busy\n");
47 return ERR_PTR(-EBUSY);
48 }
49 ssc->user++;
50 spin_unlock(&user_lock);
51
52 clk_enable(ssc->clk);
53
54 return ssc;
55 }
56 EXPORT_SYMBOL(ssc_request);
57
ssc_free(struct ssc_device * ssc)58 void ssc_free(struct ssc_device *ssc)
59 {
60 spin_lock(&user_lock);
61 if (ssc->user) {
62 ssc->user--;
63 clk_disable(ssc->clk);
64 } else {
65 dev_dbg(&ssc->pdev->dev, "device already free\n");
66 }
67 spin_unlock(&user_lock);
68 }
69 EXPORT_SYMBOL(ssc_free);
70
ssc_probe(struct platform_device * pdev)71 static int __init ssc_probe(struct platform_device *pdev)
72 {
73 int retval = 0;
74 struct resource *regs;
75 struct ssc_device *ssc;
76
77 ssc = kzalloc(sizeof(struct ssc_device), GFP_KERNEL);
78 if (!ssc) {
79 dev_dbg(&pdev->dev, "out of memory\n");
80 retval = -ENOMEM;
81 goto out;
82 }
83
84 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
85 if (!regs) {
86 dev_dbg(&pdev->dev, "no mmio resource defined\n");
87 retval = -ENXIO;
88 goto out_free;
89 }
90
91 ssc->clk = clk_get(&pdev->dev, "pclk");
92 if (IS_ERR(ssc->clk)) {
93 dev_dbg(&pdev->dev, "no pclk clock defined\n");
94 retval = -ENXIO;
95 goto out_free;
96 }
97
98 ssc->pdev = pdev;
99 ssc->regs = ioremap(regs->start, resource_size(regs));
100 if (!ssc->regs) {
101 dev_dbg(&pdev->dev, "ioremap failed\n");
102 retval = -EINVAL;
103 goto out_clk;
104 }
105
106 /* disable all interrupts */
107 clk_enable(ssc->clk);
108 ssc_writel(ssc->regs, IDR, ~0UL);
109 ssc_readl(ssc->regs, SR);
110 clk_disable(ssc->clk);
111
112 ssc->irq = platform_get_irq(pdev, 0);
113 if (!ssc->irq) {
114 dev_dbg(&pdev->dev, "could not get irq\n");
115 retval = -ENXIO;
116 goto out_unmap;
117 }
118
119 spin_lock(&user_lock);
120 list_add_tail(&ssc->list, &ssc_list);
121 spin_unlock(&user_lock);
122
123 platform_set_drvdata(pdev, ssc);
124
125 dev_info(&pdev->dev, "Atmel SSC device at 0x%p (irq %d)\n",
126 ssc->regs, ssc->irq);
127
128 goto out;
129
130 out_unmap:
131 iounmap(ssc->regs);
132 out_clk:
133 clk_put(ssc->clk);
134 out_free:
135 kfree(ssc);
136 out:
137 return retval;
138 }
139
ssc_remove(struct platform_device * pdev)140 static int __devexit ssc_remove(struct platform_device *pdev)
141 {
142 struct ssc_device *ssc = platform_get_drvdata(pdev);
143
144 spin_lock(&user_lock);
145 iounmap(ssc->regs);
146 clk_put(ssc->clk);
147 list_del(&ssc->list);
148 kfree(ssc);
149 spin_unlock(&user_lock);
150
151 return 0;
152 }
153
154 static struct platform_driver ssc_driver = {
155 .remove = __devexit_p(ssc_remove),
156 .driver = {
157 .name = "ssc",
158 .owner = THIS_MODULE,
159 },
160 };
161
ssc_init(void)162 static int __init ssc_init(void)
163 {
164 return platform_driver_probe(&ssc_driver, ssc_probe);
165 }
166 module_init(ssc_init);
167
ssc_exit(void)168 static void __exit ssc_exit(void)
169 {
170 platform_driver_unregister(&ssc_driver);
171 }
172 module_exit(ssc_exit);
173
174 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
175 MODULE_DESCRIPTION("SSC driver for Atmel AVR32 and AT91");
176 MODULE_LICENSE("GPL");
177 MODULE_ALIAS("platform:ssc");
178