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/mod_devicetable.h> 12 #include <linux/slab.h> 13 #include <linux/err.h> 14 #include <linux/clk.h> 15 #include <linux/io.h> 16 #include <linux/iopoll.h> 17 #include <linux/hw_random.h> 18 #include <linux/of.h> 19 #include <linux/platform_device.h> 20 #include <linux/pm_runtime.h> 21 22 #define TRNG_CR 0x00 23 #define TRNG_MR 0x04 24 #define TRNG_ISR 0x1c 25 #define TRNG_ISR_DATRDY BIT(0) 26 #define TRNG_ODATA 0x50 27 28 #define TRNG_KEY 0x524e4700 /* RNG */ 29 30 #define TRNG_HALFR BIT(0) /* generate RN every 168 cycles */ 31 32 struct atmel_trng_data { 33 bool has_half_rate; 34 }; 35 36 struct atmel_trng { 37 struct clk *clk; 38 void __iomem *base; 39 struct hwrng rng; 40 struct device *dev; 41 bool has_half_rate; 42 }; 43 44 static bool atmel_trng_wait_ready(struct atmel_trng *trng, bool wait) 45 { 46 int ready; 47 48 ready = readl(trng->base + TRNG_ISR) & TRNG_ISR_DATRDY; 49 if (!ready && wait) 50 readl_poll_timeout(trng->base + TRNG_ISR, ready, 51 ready & TRNG_ISR_DATRDY, 1000, 20000); 52 53 return !!ready; 54 } 55 56 static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max, 57 bool wait) 58 { 59 struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng); 60 u32 *data = buf; 61 int ret; 62 63 ret = pm_runtime_get_sync(trng->dev); 64 if (ret < 0) { 65 pm_runtime_put_sync(trng->dev); 66 return ret; 67 } 68 69 ret = atmel_trng_wait_ready(trng, wait); 70 if (!ret) 71 goto out; 72 73 *data = readl(trng->base + TRNG_ODATA); 74 /* 75 * ensure data ready is only set again AFTER the next data word is ready 76 * in case it got set between checking ISR and reading ODATA, so we 77 * don't risk re-reading the same word 78 */ 79 readl(trng->base + TRNG_ISR); 80 ret = 4; 81 82 out: 83 pm_runtime_mark_last_busy(trng->dev); 84 pm_runtime_put_sync_autosuspend(trng->dev); 85 return ret; 86 } 87 88 static int atmel_trng_init(struct atmel_trng *trng) 89 { 90 unsigned long rate; 91 int ret; 92 93 ret = clk_prepare_enable(trng->clk); 94 if (ret) 95 return ret; 96 97 if (trng->has_half_rate) { 98 rate = clk_get_rate(trng->clk); 99 100 /* if peripheral clk is above 100MHz, set HALFR */ 101 if (rate > 100000000) 102 writel(TRNG_HALFR, trng->base + TRNG_MR); 103 } 104 105 writel(TRNG_KEY | 1, trng->base + TRNG_CR); 106 107 return 0; 108 } 109 110 static void atmel_trng_cleanup(struct atmel_trng *trng) 111 { 112 writel(TRNG_KEY, trng->base + TRNG_CR); 113 clk_disable_unprepare(trng->clk); 114 } 115 116 static int atmel_trng_probe(struct platform_device *pdev) 117 { 118 struct atmel_trng *trng; 119 const struct atmel_trng_data *data; 120 int ret; 121 122 trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL); 123 if (!trng) 124 return -ENOMEM; 125 126 trng->base = devm_platform_ioremap_resource(pdev, 0); 127 if (IS_ERR(trng->base)) 128 return PTR_ERR(trng->base); 129 130 trng->clk = devm_clk_get(&pdev->dev, NULL); 131 if (IS_ERR(trng->clk)) 132 return PTR_ERR(trng->clk); 133 data = of_device_get_match_data(&pdev->dev); 134 if (!data) 135 return -ENODEV; 136 137 trng->has_half_rate = data->has_half_rate; 138 trng->dev = &pdev->dev; 139 trng->rng.name = pdev->name; 140 trng->rng.read = atmel_trng_read; 141 platform_set_drvdata(pdev, trng); 142 143 #ifndef CONFIG_PM 144 ret = atmel_trng_init(trng); 145 if (ret) 146 return ret; 147 #endif 148 149 pm_runtime_set_autosuspend_delay(&pdev->dev, 100); 150 pm_runtime_use_autosuspend(&pdev->dev); 151 pm_runtime_enable(&pdev->dev); 152 153 ret = devm_hwrng_register(&pdev->dev, &trng->rng); 154 if (ret) { 155 pm_runtime_disable(&pdev->dev); 156 pm_runtime_set_suspended(&pdev->dev); 157 #ifndef CONFIG_PM 158 atmel_trng_cleanup(trng); 159 #endif 160 } 161 162 return ret; 163 } 164 165 static void atmel_trng_remove(struct platform_device *pdev) 166 { 167 struct atmel_trng *trng = platform_get_drvdata(pdev); 168 169 atmel_trng_cleanup(trng); 170 pm_runtime_disable(&pdev->dev); 171 pm_runtime_set_suspended(&pdev->dev); 172 } 173 174 static int __maybe_unused atmel_trng_runtime_suspend(struct device *dev) 175 { 176 struct atmel_trng *trng = dev_get_drvdata(dev); 177 178 atmel_trng_cleanup(trng); 179 180 return 0; 181 } 182 183 static int __maybe_unused atmel_trng_runtime_resume(struct device *dev) 184 { 185 struct atmel_trng *trng = dev_get_drvdata(dev); 186 187 return atmel_trng_init(trng); 188 } 189 190 static const struct dev_pm_ops __maybe_unused atmel_trng_pm_ops = { 191 SET_RUNTIME_PM_OPS(atmel_trng_runtime_suspend, 192 atmel_trng_runtime_resume, NULL) 193 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, 194 pm_runtime_force_resume) 195 }; 196 197 static const struct atmel_trng_data at91sam9g45_config = { 198 .has_half_rate = false, 199 }; 200 201 static const struct atmel_trng_data sam9x60_config = { 202 .has_half_rate = true, 203 }; 204 205 static const struct of_device_id atmel_trng_dt_ids[] = { 206 { 207 .compatible = "atmel,at91sam9g45-trng", 208 .data = &at91sam9g45_config, 209 }, { 210 .compatible = "microchip,sam9x60-trng", 211 .data = &sam9x60_config, 212 }, { 213 /* sentinel */ 214 } 215 }; 216 MODULE_DEVICE_TABLE(of, atmel_trng_dt_ids); 217 218 static struct platform_driver atmel_trng_driver = { 219 .probe = atmel_trng_probe, 220 .remove = atmel_trng_remove, 221 .driver = { 222 .name = "atmel-trng", 223 .pm = pm_ptr(&atmel_trng_pm_ops), 224 .of_match_table = atmel_trng_dt_ids, 225 }, 226 }; 227 228 module_platform_driver(atmel_trng_driver); 229 230 MODULE_LICENSE("GPL"); 231 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>"); 232 MODULE_DESCRIPTION("Atmel true random number generator driver"); 233