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/platform_device.h> 12 #include <linux/hw_random.h> 13 #include <linux/delay.h> 14 #include <linux/of_irq.h> 15 #include <linux/pm_runtime.h> 16 #include <linux/of_device.h> 17 18 #define NPCM_RNGCS_REG 0x00 /* Control and status register */ 19 #define NPCM_RNGD_REG 0x04 /* Data register */ 20 #define NPCM_RNGMODE_REG 0x08 /* Mode register */ 21 22 #define NPCM_RNG_CLK_SET_62_5MHZ BIT(2) /* 60-80 MHz */ 23 #define NPCM_RNG_CLK_SET_25MHZ GENMASK(4, 3) /* 20-25 MHz */ 24 #define NPCM_RNG_DATA_VALID BIT(1) 25 #define NPCM_RNG_ENABLE BIT(0) 26 #define NPCM_RNG_M1ROSEL BIT(1) 27 28 #define NPCM_RNG_TIMEOUT_USEC 20000 29 #define NPCM_RNG_POLL_USEC 1000 30 31 #define to_npcm_rng(p) container_of(p, struct npcm_rng, rng) 32 33 struct npcm_rng { 34 void __iomem *base; 35 struct hwrng rng; 36 u32 clkp; 37 }; 38 39 static int npcm_rng_init(struct hwrng *rng) 40 { 41 struct npcm_rng *priv = to_npcm_rng(rng); 42 43 writel(priv->clkp | NPCM_RNG_ENABLE, priv->base + NPCM_RNGCS_REG); 44 45 return 0; 46 } 47 48 static void npcm_rng_cleanup(struct hwrng *rng) 49 { 50 struct npcm_rng *priv = to_npcm_rng(rng); 51 52 writel(priv->clkp, priv->base + NPCM_RNGCS_REG); 53 } 54 55 static int npcm_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) 56 { 57 struct npcm_rng *priv = to_npcm_rng(rng); 58 int retval = 0; 59 int ready; 60 61 pm_runtime_get_sync((struct device *)priv->rng.priv); 62 63 while (max) { 64 if (wait) { 65 if (readb_poll_timeout(priv->base + NPCM_RNGCS_REG, 66 ready, 67 ready & NPCM_RNG_DATA_VALID, 68 NPCM_RNG_POLL_USEC, 69 NPCM_RNG_TIMEOUT_USEC)) 70 break; 71 } else { 72 if ((readb(priv->base + NPCM_RNGCS_REG) & 73 NPCM_RNG_DATA_VALID) == 0) 74 break; 75 } 76 77 *(u8 *)buf = readb(priv->base + NPCM_RNGD_REG); 78 retval++; 79 buf++; 80 max--; 81 } 82 83 pm_runtime_mark_last_busy((struct device *)priv->rng.priv); 84 pm_runtime_put_sync_autosuspend((struct device *)priv->rng.priv); 85 86 return retval || !wait ? retval : -EIO; 87 } 88 89 static int npcm_rng_probe(struct platform_device *pdev) 90 { 91 struct npcm_rng *priv; 92 int ret; 93 94 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); 95 if (!priv) 96 return -ENOMEM; 97 98 priv->base = devm_platform_ioremap_resource(pdev, 0); 99 if (IS_ERR(priv->base)) 100 return PTR_ERR(priv->base); 101 102 dev_set_drvdata(&pdev->dev, priv); 103 pm_runtime_set_autosuspend_delay(&pdev->dev, 100); 104 pm_runtime_use_autosuspend(&pdev->dev); 105 pm_runtime_enable(&pdev->dev); 106 107 #ifndef CONFIG_PM 108 priv->rng.init = npcm_rng_init; 109 priv->rng.cleanup = npcm_rng_cleanup; 110 #endif 111 priv->rng.name = pdev->name; 112 priv->rng.read = npcm_rng_read; 113 priv->rng.priv = (unsigned long)&pdev->dev; 114 priv->clkp = (u32)(uintptr_t)of_device_get_match_data(&pdev->dev); 115 116 writel(NPCM_RNG_M1ROSEL, priv->base + NPCM_RNGMODE_REG); 117 118 ret = devm_hwrng_register(&pdev->dev, &priv->rng); 119 if (ret) { 120 dev_err(&pdev->dev, "Failed to register rng device: %d\n", 121 ret); 122 pm_runtime_disable(&pdev->dev); 123 pm_runtime_set_suspended(&pdev->dev); 124 return ret; 125 } 126 127 return 0; 128 } 129 130 static int npcm_rng_remove(struct platform_device *pdev) 131 { 132 struct npcm_rng *priv = platform_get_drvdata(pdev); 133 134 devm_hwrng_unregister(&pdev->dev, &priv->rng); 135 pm_runtime_disable(&pdev->dev); 136 pm_runtime_set_suspended(&pdev->dev); 137 138 return 0; 139 } 140 141 #ifdef CONFIG_PM 142 static int npcm_rng_runtime_suspend(struct device *dev) 143 { 144 struct npcm_rng *priv = dev_get_drvdata(dev); 145 146 npcm_rng_cleanup(&priv->rng); 147 148 return 0; 149 } 150 151 static int npcm_rng_runtime_resume(struct device *dev) 152 { 153 struct npcm_rng *priv = dev_get_drvdata(dev); 154 155 return npcm_rng_init(&priv->rng); 156 } 157 #endif 158 159 static const struct dev_pm_ops npcm_rng_pm_ops = { 160 SET_RUNTIME_PM_OPS(npcm_rng_runtime_suspend, 161 npcm_rng_runtime_resume, NULL) 162 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, 163 pm_runtime_force_resume) 164 }; 165 166 static const struct of_device_id rng_dt_id[] __maybe_unused = { 167 { .compatible = "nuvoton,npcm750-rng", 168 .data = (void *)NPCM_RNG_CLK_SET_25MHZ }, 169 { .compatible = "nuvoton,npcm845-rng", 170 .data = (void *)NPCM_RNG_CLK_SET_62_5MHZ }, 171 {}, 172 }; 173 MODULE_DEVICE_TABLE(of, rng_dt_id); 174 175 static struct platform_driver npcm_rng_driver = { 176 .driver = { 177 .name = "npcm-rng", 178 .pm = &npcm_rng_pm_ops, 179 .of_match_table = of_match_ptr(rng_dt_id), 180 }, 181 .probe = npcm_rng_probe, 182 .remove = npcm_rng_remove, 183 }; 184 185 module_platform_driver(npcm_rng_driver); 186 187 MODULE_DESCRIPTION("Nuvoton NPCM Random Number Generator Driver"); 188 MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>"); 189 MODULE_LICENSE("GPL v2"); 190