1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2006-2007 PA Semi, Inc 4 * 5 * Maintained by: Olof Johansson <olof@lixom.net> 6 * 7 * Driver for the PWRficient onchip rng 8 */ 9 10 #include <linux/module.h> 11 #include <linux/kernel.h> 12 #include <linux/platform_device.h> 13 #include <linux/hw_random.h> 14 #include <linux/delay.h> 15 #include <linux/io.h> 16 17 #define SDCRNG_CTL_REG 0x00 18 #define SDCRNG_CTL_FVLD_M 0x0000f000 19 #define SDCRNG_CTL_FVLD_S 12 20 #define SDCRNG_CTL_KSZ 0x00000800 21 #define SDCRNG_CTL_RSRC_CRG 0x00000010 22 #define SDCRNG_CTL_RSRC_RRG 0x00000000 23 #define SDCRNG_CTL_CE 0x00000004 24 #define SDCRNG_CTL_RE 0x00000002 25 #define SDCRNG_CTL_DR 0x00000001 26 #define SDCRNG_CTL_SELECT_RRG_RNG (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG) 27 #define SDCRNG_CTL_SELECT_CRG_RNG (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG) 28 #define SDCRNG_VAL_REG 0x20 29 30 #define MODULE_NAME "pasemi_rng" 31 32 static int pasemi_rng_data_present(struct hwrng *rng, int wait) 33 { 34 void __iomem *rng_regs = (void __iomem *)rng->priv; 35 int data, i; 36 37 for (i = 0; i < 20; i++) { 38 data = (in_le32(rng_regs + SDCRNG_CTL_REG) 39 & SDCRNG_CTL_FVLD_M) ? 1 : 0; 40 if (data || !wait) 41 break; 42 udelay(10); 43 } 44 return data; 45 } 46 47 static int pasemi_rng_data_read(struct hwrng *rng, u32 *data) 48 { 49 void __iomem *rng_regs = (void __iomem *)rng->priv; 50 *data = in_le32(rng_regs + SDCRNG_VAL_REG); 51 return 4; 52 } 53 54 static int pasemi_rng_init(struct hwrng *rng) 55 { 56 void __iomem *rng_regs = (void __iomem *)rng->priv; 57 u32 ctl; 58 59 ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ; 60 out_le32(rng_regs + SDCRNG_CTL_REG, ctl); 61 out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR); 62 63 return 0; 64 } 65 66 static void pasemi_rng_cleanup(struct hwrng *rng) 67 { 68 void __iomem *rng_regs = (void __iomem *)rng->priv; 69 u32 ctl; 70 71 ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE; 72 out_le32(rng_regs + SDCRNG_CTL_REG, 73 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl); 74 } 75 76 static struct hwrng pasemi_rng = { 77 .name = MODULE_NAME, 78 .init = pasemi_rng_init, 79 .cleanup = pasemi_rng_cleanup, 80 .data_present = pasemi_rng_data_present, 81 .data_read = pasemi_rng_data_read, 82 }; 83 84 static int rng_probe(struct platform_device *pdev) 85 { 86 void __iomem *rng_regs; 87 88 rng_regs = devm_platform_ioremap_resource(pdev, 0); 89 if (IS_ERR(rng_regs)) 90 return PTR_ERR(rng_regs); 91 92 pasemi_rng.priv = (unsigned long)rng_regs; 93 94 pr_info("Registering PA Semi RNG\n"); 95 return devm_hwrng_register(&pdev->dev, &pasemi_rng); 96 } 97 98 static const struct of_device_id rng_match[] = { 99 { .compatible = "1682m-rng", }, 100 { .compatible = "pasemi,pwrficient-rng", }, 101 { }, 102 }; 103 MODULE_DEVICE_TABLE(of, rng_match); 104 105 static struct platform_driver rng_driver = { 106 .driver = { 107 .name = "pasemi-rng", 108 .of_match_table = rng_match, 109 }, 110 .probe = rng_probe, 111 }; 112 113 module_platform_driver(rng_driver); 114 115 MODULE_LICENSE("GPL"); 116 MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>"); 117 MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor"); 118