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 return 0; 112 } 113 114 #ifdef CONFIG_PM 115 static int atmel_trng_suspend(struct device *dev) 116 { 117 struct atmel_trng *trng = dev_get_drvdata(dev); 118 119 clk_disable(trng->clk); 120 121 return 0; 122 } 123 124 static int atmel_trng_resume(struct device *dev) 125 { 126 struct atmel_trng *trng = dev_get_drvdata(dev); 127 128 return clk_enable(trng->clk); 129 } 130 131 static const struct dev_pm_ops atmel_trng_pm_ops = { 132 .suspend = atmel_trng_suspend, 133 .resume = atmel_trng_resume, 134 }; 135 #endif /* CONFIG_PM */ 136 137 static struct platform_driver atmel_trng_driver = { 138 .probe = atmel_trng_probe, 139 .remove = atmel_trng_remove, 140 .driver = { 141 .name = "atmel-trng", 142 .owner = THIS_MODULE, 143 #ifdef CONFIG_PM 144 .pm = &atmel_trng_pm_ops, 145 #endif /* CONFIG_PM */ 146 }, 147 }; 148 149 module_platform_driver(atmel_trng_driver); 150 151 MODULE_LICENSE("GPL"); 152 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>"); 153 MODULE_DESCRIPTION("Atmel true random number generator driver"); 154