drivers/char/hw_random/omap3-rom-rng.c

   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.rohar@gmail.com>
   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/of.h>
  22 #include <linux/of_device.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(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.rohar@gmail.com>");
 181 MODULE_LICENSE("GPL");