| 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 | struct resource *mem; |
| 178 | |
| 179 | ks_sa_rng = devm_kzalloc(dev, sizeof(*ks_sa_rng), GFP_KERNEL); |
| 180 | if (!ks_sa_rng) |
| 181 | return -ENOMEM; |
| 182 | |
| 183 | ks_sa_rng->dev = dev; |
| 184 | ks_sa_rng->rng = (struct hwrng) { |
| 185 | .name = "ks_sa_hwrng", |
| 186 | .init = ks_sa_rng_init, |
| 187 | .data_read = ks_sa_rng_data_read, |
| 188 | .data_present = ks_sa_rng_data_present, |
| 189 | .cleanup = ks_sa_rng_cleanup, |
| 190 | }; |
| 191 | ks_sa_rng->rng.priv = (unsigned long)dev; |
| 192 | |
| 193 | mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
| 194 | ks_sa_rng->reg_rng = devm_ioremap_resource(dev, mem); |
| 195 | if (IS_ERR(ks_sa_rng->reg_rng)) |
| 196 | return PTR_ERR(ks_sa_rng->reg_rng); |
| 197 | |
| 198 | ks_sa_rng->regmap_cfg = |
| 199 | syscon_regmap_lookup_by_phandle(dev->of_node, |
| 200 | "ti,syscon-sa-cfg"); |
| 201 | |
| 202 | if (IS_ERR(ks_sa_rng->regmap_cfg)) { |
| 203 | dev_err(dev, "syscon_node_to_regmap failed\n"); |
| 204 | return -EINVAL; |
| 205 | } |
| 206 | |
| 207 | pm_runtime_enable(dev); |
| 208 | ret = pm_runtime_get_sync(dev); |
| 209 | if (ret < 0) { |
| 210 | dev_err(dev, "Failed to enable SA power-domain\n"); |
| 211 | pm_runtime_disable(dev); |
| 212 | return ret; |
| 213 | } |
| 214 | |
| 215 | platform_set_drvdata(pdev, ks_sa_rng); |
| 216 | |
| 217 | return devm_hwrng_register(&pdev->dev, &ks_sa_rng->rng); |
| 218 | } |
| 219 | |
| 220 | static int ks_sa_rng_remove(struct platform_device *pdev) |
| 221 | { |
| 222 | pm_runtime_put_sync(&pdev->dev); |
| 223 | pm_runtime_disable(&pdev->dev); |
| 224 | |
| 225 | return 0; |
| 226 | } |
| 227 | |
| 228 | static const struct of_device_id ks_sa_rng_dt_match[] = { |
| 229 | { |
| 230 | .compatible = "ti,keystone-rng", |
| 231 | }, |
| 232 | { }, |
| 233 | }; |
| 234 | MODULE_DEVICE_TABLE(of, ks_sa_rng_dt_match); |
| 235 | |
| 236 | static struct platform_driver ks_sa_rng_driver = { |
| 237 | .driver = { |
| 238 | .name = "ks-sa-rng", |
| 239 | .of_match_table = ks_sa_rng_dt_match, |
| 240 | }, |
| 241 | .probe = ks_sa_rng_probe, |
| 242 | .remove = ks_sa_rng_remove, |
| 243 | }; |
| 244 | |
| 245 | module_platform_driver(ks_sa_rng_driver); |
| 246 | |
| 247 | MODULE_DESCRIPTION("Keystone NETCP SA H/W Random Number Generator driver"); |
| 248 | MODULE_AUTHOR("Vitaly Andrianov <vitalya@ti.com>"); |
| 249 | MODULE_LICENSE("GPL"); |