1 /* 2 * Copyright (C) 2006-2007 PA Semi, Inc 3 * 4 * Maintained by: Olof Johansson <olof@lixom.net> 5 * 6 * Driver for the PWRficient onchip rng 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21 22 #include <linux/module.h> 23 #include <linux/kernel.h> 24 #include <linux/platform_device.h> 25 #include <linux/hw_random.h> 26 #include <linux/delay.h> 27 #include <linux/of_address.h> 28 #include <linux/of_platform.h> 29 #include <linux/io.h> 30 31 #define SDCRNG_CTL_REG 0x00 32 #define SDCRNG_CTL_FVLD_M 0x0000f000 33 #define SDCRNG_CTL_FVLD_S 12 34 #define SDCRNG_CTL_KSZ 0x00000800 35 #define SDCRNG_CTL_RSRC_CRG 0x00000010 36 #define SDCRNG_CTL_RSRC_RRG 0x00000000 37 #define SDCRNG_CTL_CE 0x00000004 38 #define SDCRNG_CTL_RE 0x00000002 39 #define SDCRNG_CTL_DR 0x00000001 40 #define SDCRNG_CTL_SELECT_RRG_RNG (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG) 41 #define SDCRNG_CTL_SELECT_CRG_RNG (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG) 42 #define SDCRNG_VAL_REG 0x20 43 44 #define MODULE_NAME "pasemi_rng" 45 46 static int pasemi_rng_data_present(struct hwrng *rng, int wait) 47 { 48 void __iomem *rng_regs = (void __iomem *)rng->priv; 49 int data, i; 50 51 for (i = 0; i < 20; i++) { 52 data = (in_le32(rng_regs + SDCRNG_CTL_REG) 53 & SDCRNG_CTL_FVLD_M) ? 1 : 0; 54 if (data || !wait) 55 break; 56 udelay(10); 57 } 58 return data; 59 } 60 61 static int pasemi_rng_data_read(struct hwrng *rng, u32 *data) 62 { 63 void __iomem *rng_regs = (void __iomem *)rng->priv; 64 *data = in_le32(rng_regs + SDCRNG_VAL_REG); 65 return 4; 66 } 67 68 static int pasemi_rng_init(struct hwrng *rng) 69 { 70 void __iomem *rng_regs = (void __iomem *)rng->priv; 71 u32 ctl; 72 73 ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ; 74 out_le32(rng_regs + SDCRNG_CTL_REG, ctl); 75 out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR); 76 77 return 0; 78 } 79 80 static void pasemi_rng_cleanup(struct hwrng *rng) 81 { 82 void __iomem *rng_regs = (void __iomem *)rng->priv; 83 u32 ctl; 84 85 ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE; 86 out_le32(rng_regs + SDCRNG_CTL_REG, 87 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl); 88 } 89 90 static struct hwrng pasemi_rng = { 91 .name = MODULE_NAME, 92 .init = pasemi_rng_init, 93 .cleanup = pasemi_rng_cleanup, 94 .data_present = pasemi_rng_data_present, 95 .data_read = pasemi_rng_data_read, 96 }; 97 98 static int rng_probe(struct platform_device *pdev) 99 { 100 void __iomem *rng_regs; 101 struct resource *res; 102 103 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 104 rng_regs = devm_ioremap_resource(&pdev->dev, res); 105 if (IS_ERR(rng_regs)) 106 return PTR_ERR(rng_regs); 107 108 pasemi_rng.priv = (unsigned long)rng_regs; 109 110 pr_info("Registering PA Semi RNG\n"); 111 return devm_hwrng_register(&pdev->dev, &pasemi_rng); 112 } 113 114 static const struct of_device_id rng_match[] = { 115 { .compatible = "1682m-rng", }, 116 { .compatible = "pasemi,pwrficient-rng", }, 117 { }, 118 }; 119 MODULE_DEVICE_TABLE(of, rng_match); 120 121 static struct platform_driver rng_driver = { 122 .driver = { 123 .name = "pasemi-rng", 124 .of_match_table = rng_match, 125 }, 126 .probe = rng_probe, 127 }; 128 129 module_platform_driver(rng_driver); 130 131 MODULE_LICENSE("GPL"); 132 MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>"); 133 MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor"); 134