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/platform_device.h> 24 #include <linux/pm_runtime.h> 25 26 #define RNG_RESET 0x01 27 #define RNG_GEN_PRNG_HW_INIT 0x02 28 #define RNG_GEN_HW 0x08 29 30 struct omap_rom_rng { 31 struct clk *clk; 32 struct device *dev; 33 struct hwrng ops; 34 u32 (*rom_rng_call)(u32 ptr, u32 count, u32 flag); 35 }; 36 37 static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w) 38 { 39 struct omap_rom_rng *ddata; 40 u32 ptr; 41 int r; 42 43 ddata = (struct omap_rom_rng *)rng->priv; 44 45 r = pm_runtime_get_sync(ddata->dev); 46 if (r < 0) { 47 pm_runtime_put_noidle(ddata->dev); 48 49 return r; 50 } 51 52 ptr = virt_to_phys(data); 53 r = ddata->rom_rng_call(ptr, 4, RNG_GEN_HW); 54 if (r != 0) 55 r = -EINVAL; 56 else 57 r = 4; 58 59 pm_runtime_mark_last_busy(ddata->dev); 60 pm_runtime_put_autosuspend(ddata->dev); 61 62 return r; 63 } 64 65 static int __maybe_unused omap_rom_rng_runtime_suspend(struct device *dev) 66 { 67 struct omap_rom_rng *ddata; 68 int r; 69 70 ddata = dev_get_drvdata(dev); 71 72 r = ddata->rom_rng_call(0, 0, RNG_RESET); 73 if (r != 0) 74 dev_err(dev, "reset failed: %d\n", r); 75 76 clk_disable_unprepare(ddata->clk); 77 78 return 0; 79 } 80 81 static int __maybe_unused omap_rom_rng_runtime_resume(struct device *dev) 82 { 83 struct omap_rom_rng *ddata; 84 int r; 85 86 ddata = dev_get_drvdata(dev); 87 88 r = clk_prepare_enable(ddata->clk); 89 if (r < 0) 90 return r; 91 92 r = ddata->rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT); 93 if (r != 0) { 94 clk_disable_unprepare(ddata->clk); 95 dev_err(dev, "HW init failed: %d\n", r); 96 97 return -EIO; 98 } 99 100 return 0; 101 } 102 103 static void omap_rom_rng_finish(void *data) 104 { 105 struct omap_rom_rng *ddata = data; 106 107 pm_runtime_dont_use_autosuspend(ddata->dev); 108 pm_runtime_disable(ddata->dev); 109 } 110 111 static int omap3_rom_rng_probe(struct platform_device *pdev) 112 { 113 struct omap_rom_rng *ddata; 114 int ret = 0; 115 116 ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL); 117 if (!ddata) 118 return -ENOMEM; 119 120 ddata->dev = &pdev->dev; 121 ddata->ops.priv = (unsigned long)ddata; 122 ddata->ops.name = "omap3-rom"; 123 ddata->ops.read = of_device_get_match_data(&pdev->dev); 124 ddata->ops.quality = 900; 125 if (!ddata->ops.read) { 126 dev_err(&pdev->dev, "missing rom code handler\n"); 127 128 return -ENODEV; 129 } 130 dev_set_drvdata(ddata->dev, ddata); 131 132 ddata->rom_rng_call = pdev->dev.platform_data; 133 if (!ddata->rom_rng_call) { 134 dev_err(ddata->dev, "rom_rng_call is NULL\n"); 135 return -EINVAL; 136 } 137 138 ddata->clk = devm_clk_get(ddata->dev, "ick"); 139 if (IS_ERR(ddata->clk)) { 140 dev_err(ddata->dev, "unable to get RNG clock\n"); 141 return PTR_ERR(ddata->clk); 142 } 143 144 pm_runtime_enable(&pdev->dev); 145 pm_runtime_set_autosuspend_delay(&pdev->dev, 500); 146 pm_runtime_use_autosuspend(&pdev->dev); 147 148 ret = devm_add_action_or_reset(ddata->dev, omap_rom_rng_finish, 149 ddata); 150 if (ret) 151 return ret; 152 153 return devm_hwrng_register(ddata->dev, &ddata->ops); 154 } 155 156 static const struct of_device_id omap_rom_rng_match[] = { 157 { .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, }, 158 { /* sentinel */ }, 159 }; 160 MODULE_DEVICE_TABLE(of, omap_rom_rng_match); 161 162 static const struct dev_pm_ops omap_rom_rng_pm_ops = { 163 SET_SYSTEM_SLEEP_PM_OPS(omap_rom_rng_runtime_suspend, 164 omap_rom_rng_runtime_resume) 165 }; 166 167 static struct platform_driver omap3_rom_rng_driver = { 168 .driver = { 169 .name = "omap3-rom-rng", 170 .of_match_table = omap_rom_rng_match, 171 .pm = &omap_rom_rng_pm_ops, 172 }, 173 .probe = omap3_rom_rng_probe, 174 }; 175 176 module_platform_driver(omap3_rom_rng_driver); 177 178 MODULE_ALIAS("platform:omap3-rom-rng"); 179 MODULE_AUTHOR("Juha Yrjola"); 180 MODULE_AUTHOR("Pali Rohár <pali@kernel.org>"); 181 MODULE_DESCRIPTION("RNG driver for TI OMAP3 CPU family"); 182 MODULE_LICENSE("GPL"); 183