drivers/char/hw_random/ks-sa-rng.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Random Number Generator driver for the Keystone SOC
   4  *
   5  * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com
   6  *
   7  * Authors:     Sandeep Nair
   8  *              Vitaly Andrianov
   9  */
  10
  11 #include <linux/hw_random.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/io.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/clk.h>
  17 #include <linux/pm_runtime.h>
  18 #include <linux/err.h>
  19 #include <linux/regmap.h>
  20 #include <linux/mfd/syscon.h>
  21 #include <linux/of.h>
  22 #include <linux/of_address.h>
  23 #include <linux/delay.h>
  24
  25 #define SA_CMD_STATUS_OFS                       0x8
  26
  27 /* TRNG enable control in SA System module*/
  28 #define SA_CMD_STATUS_REG_TRNG_ENABLE           BIT(3)
  29
  30 /* TRNG start control in TRNG module */
  31 #define TRNG_CNTL_REG_TRNG_ENABLE               BIT(10)
  32
  33 /* Data ready indicator in STATUS register */
  34 #define TRNG_STATUS_REG_READY                   BIT(0)
  35
  36 /* Data ready clear control in INTACK register */
  37 #define TRNG_INTACK_REG_READY                   BIT(0)
  38
  39 /*
  40  * Number of samples taken to gather entropy during startup.
  41  * If value is 0, the number of samples is 2^24 else
  42  * equals value times 2^8.
  43  */
  44 #define TRNG_DEF_STARTUP_CYCLES                 0
  45 #define TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT      16
  46
  47 /*
  48  * Minimum number of samples taken to regenerate entropy
  49  * If value is 0, the number of samples is 2^24 else
  50  * equals value times 2^6.
  51  */
  52 #define TRNG_DEF_MIN_REFILL_CYCLES              1
  53 #define TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT    0
  54
  55 /*
  56  * Maximum number of samples taken to regenerate entropy
  57  * If value is 0, the number of samples is 2^24 else
  58  * equals value times 2^8.
  59  */
  60 #define TRNG_DEF_MAX_REFILL_CYCLES              0
  61 #define TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT    16
  62
  63 /* Number of CLK input cycles between samples */
  64 #define TRNG_DEF_CLK_DIV_CYCLES                 0
  65 #define TRNG_CFG_REG_SAMPLE_DIV_SHIFT           8
  66
  67 /* Maximum retries to get rng data */
  68 #define SA_MAX_RNG_DATA_RETRIES                 5
  69 /* Delay between retries (in usecs) */
  70 #define SA_RNG_DATA_RETRY_DELAY                 5
  71
  72 struct trng_regs {
  73         u32     output_l;
  74         u32     output_h;
  75         u32     status;
  76         u32     intmask;
  77         u32     intack;
  78         u32     control;
  79         u32     config;
  80 };
  81
  82 struct ks_sa_rng {
  83         struct device   *dev;
  84         struct hwrng    rng;
  85         struct clk      *clk;
  86         struct regmap   *regmap_cfg;
  87         struct trng_regs __iomem *reg_rng;
  88 };
  89
  90 static int ks_sa_rng_init(struct hwrng *rng)
  91 {
  92         u32 value;
  93         struct device *dev = (struct device *)rng->priv;
  94         struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
  95
  96         /* Enable RNG module */
  97         regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
  98                           SA_CMD_STATUS_REG_TRNG_ENABLE,
  99                           SA_CMD_STATUS_REG_TRNG_ENABLE);
 100
 101         /* Configure RNG module */
 102         writel(0, &ks_sa_rng->reg_rng->control);
 103         value = TRNG_DEF_STARTUP_CYCLES << TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT;
 104         writel(value, &ks_sa_rng->reg_rng->control);
 105
 106         value = (TRNG_DEF_MIN_REFILL_CYCLES <<
 107                  TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT) |
 108                 (TRNG_DEF_MAX_REFILL_CYCLES <<
 109                  TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT) |
 110                 (TRNG_DEF_CLK_DIV_CYCLES <<
 111                  TRNG_CFG_REG_SAMPLE_DIV_SHIFT);
 112
 113         writel(value, &ks_sa_rng->reg_rng->config);
 114
 115         /* Disable all interrupts from TRNG */
 116         writel(0, &ks_sa_rng->reg_rng->intmask);
 117
 118         /* Enable RNG */
 119         value = readl(&ks_sa_rng->reg_rng->control);
 120         value |= TRNG_CNTL_REG_TRNG_ENABLE;
 121         writel(value, &ks_sa_rng->reg_rng->control);
 122
 123         return 0;
 124 }
 125
 126 static void ks_sa_rng_cleanup(struct hwrng *rng)
 127 {
 128         struct device *dev = (struct device *)rng->priv;
 129         struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
 130
 131         /* Disable RNG */
 132         writel(0, &ks_sa_rng->reg_rng->control);
 133         regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
 134                           SA_CMD_STATUS_REG_TRNG_ENABLE, 0);
 135 }
 136
 137 static int ks_sa_rng_data_read(struct hwrng *rng, u32 *data)
 138 {
 139         struct device *dev = (struct device *)rng->priv;
 140         struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
 141
 142         /* Read random data */
 143         data[0] = readl(&ks_sa_rng->reg_rng->output_l);
 144         data[1] = readl(&ks_sa_rng->reg_rng->output_h);
 145
 146         writel(TRNG_INTACK_REG_READY, &ks_sa_rng->reg_rng->intack);
 147
 148         return sizeof(u32) * 2;
 149 }
 150
 151 static int ks_sa_rng_data_present(struct hwrng *rng, int wait)
 152 {
 153         struct device *dev = (struct device *)rng->priv;
 154         struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
 155
 156         u32     ready;
 157         int     j;
 158
 159         for (j = 0; j < SA_MAX_RNG_DATA_RETRIES; j++) {
 160                 ready = readl(&ks_sa_rng->reg_rng->status);
 161                 ready &= TRNG_STATUS_REG_READY;
 162
 163                 if (ready || !wait)
 164                         break;
 165
 166                 udelay(SA_RNG_DATA_RETRY_DELAY);
 167         }
 168
 169         return ready;
 170 }
 171
 172 static int ks_sa_rng_probe(struct platform_device *pdev)
 173 {
 174         struct ks_sa_rng        *ks_sa_rng;
 175         struct device           *dev = &pdev->dev;
 176         int                     ret;
 177
 178         ks_sa_rng = devm_kzalloc(dev, sizeof(*ks_sa_rng), GFP_KERNEL);
 179         if (!ks_sa_rng)
 180                 return -ENOMEM;
 181
 182         ks_sa_rng->dev = dev;
 183         ks_sa_rng->rng = (struct hwrng) {
 184                 .name = "ks_sa_hwrng",
 185                 .init = ks_sa_rng_init,
 186                 .data_read = ks_sa_rng_data_read,
 187                 .data_present = ks_sa_rng_data_present,
 188                 .cleanup = ks_sa_rng_cleanup,
 189         };
 190         ks_sa_rng->rng.priv = (unsigned long)dev;
 191
 192         ks_sa_rng->reg_rng = devm_platform_ioremap_resource(pdev, 0);
 193         if (IS_ERR(ks_sa_rng->reg_rng))
 194                 return PTR_ERR(ks_sa_rng->reg_rng);
 195
 196         ks_sa_rng->regmap_cfg =
 197                 syscon_regmap_lookup_by_phandle(dev->of_node,
 198                                                 "ti,syscon-sa-cfg");
 199
 200         if (IS_ERR(ks_sa_rng->regmap_cfg)) {
 201                 dev_err(dev, "syscon_node_to_regmap failed\n");
 202                 return -EINVAL;
 203         }
 204
 205         pm_runtime_enable(dev);
 206         ret = pm_runtime_get_sync(dev);
 207         if (ret < 0) {
 208                 dev_err(dev, "Failed to enable SA power-domain\n");
 209                 pm_runtime_disable(dev);
 210                 return ret;
 211         }
 212
 213         platform_set_drvdata(pdev, ks_sa_rng);
 214
 215         return devm_hwrng_register(&pdev->dev, &ks_sa_rng->rng);
 216 }
 217
 218 static int ks_sa_rng_remove(struct platform_device *pdev)
 219 {
 220         pm_runtime_put_sync(&pdev->dev);
 221         pm_runtime_disable(&pdev->dev);
 222
 223         return 0;
 224 }
 225
 226 static const struct of_device_id ks_sa_rng_dt_match[] = {
 227         {
 228                 .compatible = "ti,keystone-rng",
 229         },
 230         { },
 231 };
 232 MODULE_DEVICE_TABLE(of, ks_sa_rng_dt_match);
 233
 234 static struct platform_driver ks_sa_rng_driver = {
 235         .driver         = {
 236                 .name   = "ks-sa-rng",
 237                 .of_match_table = ks_sa_rng_dt_match,
 238         },
 239         .probe          = ks_sa_rng_probe,
 240         .remove         = ks_sa_rng_remove,
 241 };
 242
 243 module_platform_driver(ks_sa_rng_driver);
 244
 245 MODULE_DESCRIPTION("Keystone NETCP SA H/W Random Number Generator driver");
 246 MODULE_AUTHOR("Vitaly Andrianov <vitalya@ti.com>");
 247 MODULE_LICENSE("GPL");