1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2019 Nuvoton Technology corporation. 3 4 #include <linux/kernel.h> 5 #include <linux/module.h> 6 #include <linux/io.h> 7 #include <linux/iopoll.h> 8 #include <linux/init.h> 9 #include <linux/random.h> 10 #include <linux/err.h> 11 #include <linux/of.h> 12 #include <linux/platform_device.h> 13 #include <linux/hw_random.h> 14 #include <linux/delay.h> 15 #include <linux/pm_runtime.h> 16 17 #define NPCM_RNGCS_REG 0x00 /* Control and status register */ 18 #define NPCM_RNGD_REG 0x04 /* Data register */ 19 #define NPCM_RNGMODE_REG 0x08 /* Mode register */ 20 21 #define NPCM_RNG_CLK_SET_62_5MHZ BIT(2) /* 60-80 MHz */ 22 #define NPCM_RNG_CLK_SET_25MHZ GENMASK(4, 3) /* 20-25 MHz */ 23 #define NPCM_RNG_DATA_VALID BIT(1) 24 #define NPCM_RNG_ENABLE BIT(0) 25 #define NPCM_RNG_M1ROSEL BIT(1) 26 27 #define NPCM_RNG_TIMEOUT_USEC 20000 28 #define NPCM_RNG_POLL_USEC 1000 29 30 #define to_npcm_rng(p) container_of(p, struct npcm_rng, rng) 31 32 struct npcm_rng { 33 void __iomem *base; 34 struct hwrng rng; 35 u32 clkp; 36 }; 37 38 static int npcm_rng_init(struct hwrng *rng) 39 { 40 struct npcm_rng *priv = to_npcm_rng(rng); 41 42 writel(priv->clkp | NPCM_RNG_ENABLE, priv->base + NPCM_RNGCS_REG); 43 44 return 0; 45 } 46 47 static void npcm_rng_cleanup(struct hwrng *rng) 48 { 49 struct npcm_rng *priv = to_npcm_rng(rng); 50 51 writel(priv->clkp, priv->base + NPCM_RNGCS_REG); 52 } 53 54 static int npcm_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) 55 { 56 struct npcm_rng *priv = to_npcm_rng(rng); 57 int retval = 0; 58 int ready; 59 60 pm_runtime_get_sync((struct device *)priv->rng.priv); 61 62 while (max) { 63 if (wait) { 64 if (readb_poll_timeout(priv->base + NPCM_RNGCS_REG, 65 ready, 66 ready & NPCM_RNG_DATA_VALID, 67 NPCM_RNG_POLL_USEC, 68 NPCM_RNG_TIMEOUT_USEC)) 69 break; 70 } else { 71 if ((readb(priv->base + NPCM_RNGCS_REG) & 72 NPCM_RNG_DATA_VALID) == 0) 73 break; 74 } 75 76 *(u8 *)buf = readb(priv->base + NPCM_RNGD_REG); 77 retval++; 78 buf++; 79 max--; 80 } 81 82 pm_runtime_mark_last_busy((struct device *)priv->rng.priv); 83 pm_runtime_put_sync_autosuspend((struct device *)priv->rng.priv); 84 85 return retval || !wait ? retval : -EIO; 86 } 87 88 static int npcm_rng_probe(struct platform_device *pdev) 89 { 90 struct npcm_rng *priv; 91 int ret; 92 93 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); 94 if (!priv) 95 return -ENOMEM; 96 97 priv->base = devm_platform_ioremap_resource(pdev, 0); 98 if (IS_ERR(priv->base)) 99 return PTR_ERR(priv->base); 100 101 dev_set_drvdata(&pdev->dev, priv); 102 pm_runtime_set_autosuspend_delay(&pdev->dev, 100); 103 pm_runtime_use_autosuspend(&pdev->dev); 104 pm_runtime_enable(&pdev->dev); 105 106 #ifndef CONFIG_PM 107 priv->rng.init = npcm_rng_init; 108 priv->rng.cleanup = npcm_rng_cleanup; 109 #endif 110 priv->rng.name = pdev->name; 111 priv->rng.read = npcm_rng_read; 112 priv->rng.priv = (unsigned long)&pdev->dev; 113 priv->clkp = (u32)(uintptr_t)of_device_get_match_data(&pdev->dev); 114 115 writel(NPCM_RNG_M1ROSEL, priv->base + NPCM_RNGMODE_REG); 116 117 ret = devm_hwrng_register(&pdev->dev, &priv->rng); 118 if (ret) { 119 dev_err(&pdev->dev, "Failed to register rng device: %d\n", 120 ret); 121 pm_runtime_disable(&pdev->dev); 122 pm_runtime_set_suspended(&pdev->dev); 123 return ret; 124 } 125 126 return 0; 127 } 128 129 static void npcm_rng_remove(struct platform_device *pdev) 130 { 131 struct npcm_rng *priv = platform_get_drvdata(pdev); 132 133 devm_hwrng_unregister(&pdev->dev, &priv->rng); 134 pm_runtime_disable(&pdev->dev); 135 pm_runtime_set_suspended(&pdev->dev); 136 } 137 138 #ifdef CONFIG_PM 139 static int npcm_rng_runtime_suspend(struct device *dev) 140 { 141 struct npcm_rng *priv = dev_get_drvdata(dev); 142 143 npcm_rng_cleanup(&priv->rng); 144 145 return 0; 146 } 147 148 static int npcm_rng_runtime_resume(struct device *dev) 149 { 150 struct npcm_rng *priv = dev_get_drvdata(dev); 151 152 return npcm_rng_init(&priv->rng); 153 } 154 #endif 155 156 static const struct dev_pm_ops npcm_rng_pm_ops = { 157 SET_RUNTIME_PM_OPS(npcm_rng_runtime_suspend, 158 npcm_rng_runtime_resume, NULL) 159 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, 160 pm_runtime_force_resume) 161 }; 162 163 static const struct of_device_id rng_dt_id[] __maybe_unused = { 164 { .compatible = "nuvoton,npcm750-rng", 165 .data = (void *)NPCM_RNG_CLK_SET_25MHZ }, 166 { .compatible = "nuvoton,npcm845-rng", 167 .data = (void *)NPCM_RNG_CLK_SET_62_5MHZ }, 168 {}, 169 }; 170 MODULE_DEVICE_TABLE(of, rng_dt_id); 171 172 static struct platform_driver npcm_rng_driver = { 173 .driver = { 174 .name = "npcm-rng", 175 .pm = &npcm_rng_pm_ops, 176 .of_match_table = of_match_ptr(rng_dt_id), 177 }, 178 .probe = npcm_rng_probe, 179 .remove_new = npcm_rng_remove, 180 }; 181 182 module_platform_driver(npcm_rng_driver); 183 184 MODULE_DESCRIPTION("Nuvoton NPCM Random Number Generator Driver"); 185 MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>"); 186 MODULE_LICENSE("GPL v2"); 187