1 /* 2 * omap3-rom-rng.c - RNG driver for TI OMAP3 CPU family 3 * 4 * Copyright (C) 2009 Nokia Corporation 5 * Author: Juha Yrjola <juha.yrjola@solidboot.com> 6 * 7 * Copyright (C) 2013 Pali Rohár <pali@kernel.org> 8 * 9 * This file is licensed under the terms of the GNU General Public 10 * License version 2. This program is licensed "as is" without any 11 * warranty of any kind, whether express or implied. 12 */ 13 14 #include <linux/module.h> 15 #include <linux/init.h> 16 #include <linux/random.h> 17 #include <linux/hw_random.h> 18 #include <linux/workqueue.h> 19 #include <linux/clk.h> 20 #include <linux/err.h> 21 #include <linux/io.h> 22 #include <linux/of.h> 23 #include <linux/of_device.h> 24 #include <linux/platform_device.h> 25 #include <linux/pm_runtime.h> 26 27 #define RNG_RESET 0x01 28 #define RNG_GEN_PRNG_HW_INIT 0x02 29 #define RNG_GEN_HW 0x08 30 31 struct omap_rom_rng { 32 struct clk *clk; 33 struct device *dev; 34 struct hwrng ops; 35 u32 (*rom_rng_call)(u32 ptr, u32 count, u32 flag); 36 }; 37 38 static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w) 39 { 40 struct omap_rom_rng *ddata; 41 u32 ptr; 42 int r; 43 44 ddata = (struct omap_rom_rng *)rng->priv; 45 46 r = pm_runtime_get_sync(ddata->dev); 47 if (r < 0) { 48 pm_runtime_put_noidle(ddata->dev); 49 50 return r; 51 } 52 53 ptr = virt_to_phys(data); 54 r = ddata->rom_rng_call(ptr, 4, RNG_GEN_HW); 55 if (r != 0) 56 r = -EINVAL; 57 else 58 r = 4; 59 60 pm_runtime_mark_last_busy(ddata->dev); 61 pm_runtime_put_autosuspend(ddata->dev); 62 63 return r; 64 } 65 66 static int __maybe_unused omap_rom_rng_runtime_suspend(struct device *dev) 67 { 68 struct omap_rom_rng *ddata; 69 int r; 70 71 ddata = dev_get_drvdata(dev); 72 73 r = ddata->rom_rng_call(0, 0, RNG_RESET); 74 if (r != 0) 75 dev_err(dev, "reset failed: %d\n", r); 76 77 clk_disable_unprepare(ddata->clk); 78 79 return 0; 80 } 81 82 static int __maybe_unused omap_rom_rng_runtime_resume(struct device *dev) 83 { 84 struct omap_rom_rng *ddata; 85 int r; 86 87 ddata = dev_get_drvdata(dev); 88 89 r = clk_prepare_enable(ddata->clk); 90 if (r < 0) 91 return r; 92 93 r = ddata->rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT); 94 if (r != 0) { 95 clk_disable(ddata->clk); 96 dev_err(dev, "HW init failed: %d\n", r); 97 98 return -EIO; 99 } 100 101 return 0; 102 } 103 104 static void omap_rom_rng_finish(void *data) 105 { 106 struct omap_rom_rng *ddata = data; 107 108 pm_runtime_dont_use_autosuspend(ddata->dev); 109 pm_runtime_disable(ddata->dev); 110 } 111 112 static int omap3_rom_rng_probe(struct platform_device *pdev) 113 { 114 struct omap_rom_rng *ddata; 115 int ret = 0; 116 117 ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL); 118 if (!ddata) 119 return -ENOMEM; 120 121 ddata->dev = &pdev->dev; 122 ddata->ops.priv = (unsigned long)ddata; 123 ddata->ops.name = "omap3-rom"; 124 ddata->ops.read = of_device_get_match_data(&pdev->dev); 125 ddata->ops.quality = 900; 126 if (!ddata->ops.read) { 127 dev_err(&pdev->dev, "missing rom code handler\n"); 128 129 return -ENODEV; 130 } 131 dev_set_drvdata(ddata->dev, ddata); 132 133 ddata->rom_rng_call = pdev->dev.platform_data; 134 if (!ddata->rom_rng_call) { 135 dev_err(ddata->dev, "rom_rng_call is NULL\n"); 136 return -EINVAL; 137 } 138 139 ddata->clk = devm_clk_get(ddata->dev, "ick"); 140 if (IS_ERR(ddata->clk)) { 141 dev_err(ddata->dev, "unable to get RNG clock\n"); 142 return PTR_ERR(ddata->clk); 143 } 144 145 pm_runtime_enable(&pdev->dev); 146 pm_runtime_set_autosuspend_delay(&pdev->dev, 500); 147 pm_runtime_use_autosuspend(&pdev->dev); 148 149 ret = devm_add_action_or_reset(ddata->dev, omap_rom_rng_finish, 150 ddata); 151 if (ret) 152 return ret; 153 154 return devm_hwrng_register(ddata->dev, &ddata->ops); 155 } 156 157 static const struct of_device_id omap_rom_rng_match[] = { 158 { .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, }, 159 { /* sentinel */ }, 160 }; 161 MODULE_DEVICE_TABLE(of, omap_rom_rng_match); 162 163 static const struct dev_pm_ops omap_rom_rng_pm_ops = { 164 SET_SYSTEM_SLEEP_PM_OPS(omap_rom_rng_runtime_suspend, 165 omap_rom_rng_runtime_resume) 166 }; 167 168 static struct platform_driver omap3_rom_rng_driver = { 169 .driver = { 170 .name = "omap3-rom-rng", 171 .of_match_table = omap_rom_rng_match, 172 .pm = &omap_rom_rng_pm_ops, 173 }, 174 .probe = omap3_rom_rng_probe, 175 }; 176 177 module_platform_driver(omap3_rom_rng_driver); 178 179 MODULE_ALIAS("platform:omap3-rom-rng"); 180 MODULE_AUTHOR("Juha Yrjola"); 181 MODULE_AUTHOR("Pali Rohár <pali@kernel.org>"); 182 MODULE_LICENSE("GPL"); 183