1 /* 2 * Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk> 3 * 4 * This file is licensed under the terms of the GNU General Public 5 * License version 2. This program is licensed "as is" without any 6 * warranty of any kind, whether express or implied. 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/slab.h> 12 #include <linux/err.h> 13 #include <linux/clk.h> 14 #include <linux/io.h> 15 #include <linux/hw_random.h> 16 #include <linux/platform_device.h> 17 18 #define TRNG_CR 0x00 19 #define TRNG_ISR 0x1c 20 #define TRNG_ODATA 0x50 21 22 #define TRNG_KEY 0x524e4700 /* RNG */ 23 24 struct atmel_trng { 25 struct clk *clk; 26 void __iomem *base; 27 struct hwrng rng; 28 }; 29 30 static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max, 31 bool wait) 32 { 33 struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng); 34 u32 *data = buf; 35 36 /* data ready? */ 37 if (readl(trng->base + TRNG_ISR) & 1) { 38 *data = readl(trng->base + TRNG_ODATA); 39 /* 40 ensure data ready is only set again AFTER the next data 41 word is ready in case it got set between checking ISR 42 and reading ODATA, so we don't risk re-reading the 43 same word 44 */ 45 readl(trng->base + TRNG_ISR); 46 return 4; 47 } else 48 return 0; 49 } 50 51 static int atmel_trng_probe(struct platform_device *pdev) 52 { 53 struct atmel_trng *trng; 54 struct resource *res; 55 int ret; 56 57 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 58 if (!res) 59 return -EINVAL; 60 61 trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL); 62 if (!trng) 63 return -ENOMEM; 64 65 if (!devm_request_mem_region(&pdev->dev, res->start, 66 resource_size(res), pdev->name)) 67 return -EBUSY; 68 69 trng->base = devm_ioremap(&pdev->dev, res->start, resource_size(res)); 70 if (!trng->base) 71 return -EBUSY; 72 73 trng->clk = clk_get(&pdev->dev, NULL); 74 if (IS_ERR(trng->clk)) 75 return PTR_ERR(trng->clk); 76 77 ret = clk_enable(trng->clk); 78 if (ret) 79 goto err_enable; 80 81 writel(TRNG_KEY | 1, trng->base + TRNG_CR); 82 trng->rng.name = pdev->name; 83 trng->rng.read = atmel_trng_read; 84 85 ret = hwrng_register(&trng->rng); 86 if (ret) 87 goto err_register; 88 89 platform_set_drvdata(pdev, trng); 90 91 return 0; 92 93 err_register: 94 clk_disable(trng->clk); 95 err_enable: 96 clk_put(trng->clk); 97 98 return ret; 99 } 100 101 static int atmel_trng_remove(struct platform_device *pdev) 102 { 103 struct atmel_trng *trng = platform_get_drvdata(pdev); 104 105 hwrng_unregister(&trng->rng); 106 107 writel(TRNG_KEY, trng->base + TRNG_CR); 108 clk_disable(trng->clk); 109 clk_put(trng->clk); 110 111 platform_set_drvdata(pdev, NULL); 112 113 return 0; 114 } 115 116 #ifdef CONFIG_PM 117 static int atmel_trng_suspend(struct device *dev) 118 { 119 struct atmel_trng *trng = dev_get_drvdata(dev); 120 121 clk_disable(trng->clk); 122 123 return 0; 124 } 125 126 static int atmel_trng_resume(struct device *dev) 127 { 128 struct atmel_trng *trng = dev_get_drvdata(dev); 129 130 return clk_enable(trng->clk); 131 } 132 133 static const struct dev_pm_ops atmel_trng_pm_ops = { 134 .suspend = atmel_trng_suspend, 135 .resume = atmel_trng_resume, 136 }; 137 #endif /* CONFIG_PM */ 138 139 static struct platform_driver atmel_trng_driver = { 140 .probe = atmel_trng_probe, 141 .remove = __devexit_p(atmel_trng_remove), 142 .driver = { 143 .name = "atmel-trng", 144 .owner = THIS_MODULE, 145 #ifdef CONFIG_PM 146 .pm = &atmel_trng_pm_ops, 147 #endif /* CONFIG_PM */ 148 }, 149 }; 150 151 module_platform_driver(atmel_trng_driver); 152 153 MODULE_LICENSE("GPL"); 154 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>"); 155 MODULE_DESCRIPTION("Atmel true random number generator driver"); 156