mxc-rnga.c (5287B)
1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * RNG driver for Freescale RNGA 4 * 5 * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved. 6 * Author: Alan Carvalho de Assis <acassis@gmail.com> 7 */ 8 9/* 10 * 11 * This driver is based on other RNG drivers. 12 */ 13 14#include <linux/clk.h> 15#include <linux/delay.h> 16#include <linux/hw_random.h> 17#include <linux/io.h> 18#include <linux/module.h> 19#include <linux/of.h> 20#include <linux/platform_device.h> 21 22/* RNGA Registers */ 23#define RNGA_CONTROL 0x00 24#define RNGA_STATUS 0x04 25#define RNGA_ENTROPY 0x08 26#define RNGA_OUTPUT_FIFO 0x0c 27#define RNGA_MODE 0x10 28#define RNGA_VERIFICATION_CONTROL 0x14 29#define RNGA_OSC_CONTROL_COUNTER 0x18 30#define RNGA_OSC1_COUNTER 0x1c 31#define RNGA_OSC2_COUNTER 0x20 32#define RNGA_OSC_COUNTER_STATUS 0x24 33 34/* RNGA Registers Range */ 35#define RNG_ADDR_RANGE 0x28 36 37/* RNGA Control Register */ 38#define RNGA_CONTROL_SLEEP 0x00000010 39#define RNGA_CONTROL_CLEAR_INT 0x00000008 40#define RNGA_CONTROL_MASK_INTS 0x00000004 41#define RNGA_CONTROL_HIGH_ASSURANCE 0x00000002 42#define RNGA_CONTROL_GO 0x00000001 43 44#define RNGA_STATUS_LEVEL_MASK 0x0000ff00 45 46/* RNGA Status Register */ 47#define RNGA_STATUS_OSC_DEAD 0x80000000 48#define RNGA_STATUS_SLEEP 0x00000010 49#define RNGA_STATUS_ERROR_INT 0x00000008 50#define RNGA_STATUS_FIFO_UNDERFLOW 0x00000004 51#define RNGA_STATUS_LAST_READ_STATUS 0x00000002 52#define RNGA_STATUS_SECURITY_VIOLATION 0x00000001 53 54struct mxc_rng { 55 struct device *dev; 56 struct hwrng rng; 57 void __iomem *mem; 58 struct clk *clk; 59}; 60 61static int mxc_rnga_data_present(struct hwrng *rng, int wait) 62{ 63 int i; 64 struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng); 65 66 for (i = 0; i < 20; i++) { 67 /* how many random numbers are in FIFO? [0-16] */ 68 int level = (__raw_readl(mxc_rng->mem + RNGA_STATUS) & 69 RNGA_STATUS_LEVEL_MASK) >> 8; 70 if (level || !wait) 71 return !!level; 72 udelay(10); 73 } 74 return 0; 75} 76 77static int mxc_rnga_data_read(struct hwrng *rng, u32 * data) 78{ 79 int err; 80 u32 ctrl; 81 struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng); 82 83 /* retrieve a random number from FIFO */ 84 *data = __raw_readl(mxc_rng->mem + RNGA_OUTPUT_FIFO); 85 86 /* some error while reading this random number? */ 87 err = __raw_readl(mxc_rng->mem + RNGA_STATUS) & RNGA_STATUS_ERROR_INT; 88 89 /* if error: clear error interrupt, but doesn't return random number */ 90 if (err) { 91 dev_dbg(mxc_rng->dev, "Error while reading random number!\n"); 92 ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL); 93 __raw_writel(ctrl | RNGA_CONTROL_CLEAR_INT, 94 mxc_rng->mem + RNGA_CONTROL); 95 return 0; 96 } else 97 return 4; 98} 99 100static int mxc_rnga_init(struct hwrng *rng) 101{ 102 u32 ctrl, osc; 103 struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng); 104 105 /* wake up */ 106 ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL); 107 __raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, mxc_rng->mem + RNGA_CONTROL); 108 109 /* verify if oscillator is working */ 110 osc = __raw_readl(mxc_rng->mem + RNGA_STATUS); 111 if (osc & RNGA_STATUS_OSC_DEAD) { 112 dev_err(mxc_rng->dev, "RNGA Oscillator is dead!\n"); 113 return -ENODEV; 114 } 115 116 /* go running */ 117 ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL); 118 __raw_writel(ctrl | RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL); 119 120 return 0; 121} 122 123static void mxc_rnga_cleanup(struct hwrng *rng) 124{ 125 u32 ctrl; 126 struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng); 127 128 ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL); 129 130 /* stop rnga */ 131 __raw_writel(ctrl & ~RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL); 132} 133 134static int __init mxc_rnga_probe(struct platform_device *pdev) 135{ 136 int err; 137 struct mxc_rng *mxc_rng; 138 139 mxc_rng = devm_kzalloc(&pdev->dev, sizeof(*mxc_rng), GFP_KERNEL); 140 if (!mxc_rng) 141 return -ENOMEM; 142 143 mxc_rng->dev = &pdev->dev; 144 mxc_rng->rng.name = "mxc-rnga"; 145 mxc_rng->rng.init = mxc_rnga_init; 146 mxc_rng->rng.cleanup = mxc_rnga_cleanup; 147 mxc_rng->rng.data_present = mxc_rnga_data_present; 148 mxc_rng->rng.data_read = mxc_rnga_data_read; 149 150 mxc_rng->clk = devm_clk_get(&pdev->dev, NULL); 151 if (IS_ERR(mxc_rng->clk)) { 152 dev_err(&pdev->dev, "Could not get rng_clk!\n"); 153 return PTR_ERR(mxc_rng->clk); 154 } 155 156 err = clk_prepare_enable(mxc_rng->clk); 157 if (err) 158 return err; 159 160 mxc_rng->mem = devm_platform_ioremap_resource(pdev, 0); 161 if (IS_ERR(mxc_rng->mem)) { 162 err = PTR_ERR(mxc_rng->mem); 163 goto err_ioremap; 164 } 165 166 err = hwrng_register(&mxc_rng->rng); 167 if (err) { 168 dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err); 169 goto err_ioremap; 170 } 171 172 return 0; 173 174err_ioremap: 175 clk_disable_unprepare(mxc_rng->clk); 176 return err; 177} 178 179static int __exit mxc_rnga_remove(struct platform_device *pdev) 180{ 181 struct mxc_rng *mxc_rng = platform_get_drvdata(pdev); 182 183 hwrng_unregister(&mxc_rng->rng); 184 185 clk_disable_unprepare(mxc_rng->clk); 186 187 return 0; 188} 189 190static const struct of_device_id mxc_rnga_of_match[] = { 191 { .compatible = "fsl,imx21-rnga", }, 192 { .compatible = "fsl,imx31-rnga", }, 193 { /* sentinel */ }, 194}; 195MODULE_DEVICE_TABLE(of, mxc_rnga_of_match); 196 197static struct platform_driver mxc_rnga_driver = { 198 .driver = { 199 .name = "mxc_rnga", 200 .of_match_table = mxc_rnga_of_match, 201 }, 202 .remove = __exit_p(mxc_rnga_remove), 203}; 204 205module_platform_driver_probe(mxc_rnga_driver, mxc_rnga_probe); 206 207MODULE_AUTHOR("Freescale Semiconductor, Inc."); 208MODULE_DESCRIPTION("H/W RNGA driver for i.MX"); 209MODULE_LICENSE("GPL");