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 54 struct mxc_rng { 55 struct device *dev; 56 struct hwrng rng; 57 void __iomem *mem; 58 struct clk *clk; 59 }; 60 61 static 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 77 static 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 } 99 100 static 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 } 122 123 static 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 } 133 134 static int __init mxc_rnga_probe(struct platform_device *pdev) 135 { 136 int err; 137 struct resource *res; 138 struct mxc_rng *mxc_rng; 139 140 mxc_rng = devm_kzalloc(&pdev->dev, sizeof(*mxc_rng), GFP_KERNEL); 141 if (!mxc_rng) 142 return -ENOMEM; 143 144 mxc_rng->dev = &pdev->dev; 145 mxc_rng->rng.name = "mxc-rnga"; 146 mxc_rng->rng.init = mxc_rnga_init; 147 mxc_rng->rng.cleanup = mxc_rnga_cleanup, 148 mxc_rng->rng.data_present = mxc_rnga_data_present, 149 mxc_rng->rng.data_read = mxc_rnga_data_read, 150 151 mxc_rng->clk = devm_clk_get(&pdev->dev, NULL); 152 if (IS_ERR(mxc_rng->clk)) { 153 dev_err(&pdev->dev, "Could not get rng_clk!\n"); 154 return PTR_ERR(mxc_rng->clk); 155 } 156 157 err = clk_prepare_enable(mxc_rng->clk); 158 if (err) 159 return err; 160 161 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 162 mxc_rng->mem = devm_ioremap_resource(&pdev->dev, res); 163 if (IS_ERR(mxc_rng->mem)) { 164 err = PTR_ERR(mxc_rng->mem); 165 goto err_ioremap; 166 } 167 168 err = hwrng_register(&mxc_rng->rng); 169 if (err) { 170 dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err); 171 goto err_ioremap; 172 } 173 174 return 0; 175 176 err_ioremap: 177 clk_disable_unprepare(mxc_rng->clk); 178 return err; 179 } 180 181 static int __exit mxc_rnga_remove(struct platform_device *pdev) 182 { 183 struct mxc_rng *mxc_rng = platform_get_drvdata(pdev); 184 185 hwrng_unregister(&mxc_rng->rng); 186 187 clk_disable_unprepare(mxc_rng->clk); 188 189 return 0; 190 } 191 192 static const struct of_device_id mxc_rnga_of_match[] = { 193 { .compatible = "fsl,imx21-rnga", }, 194 { .compatible = "fsl,imx31-rnga", }, 195 { /* sentinel */ }, 196 }; 197 MODULE_DEVICE_TABLE(of, mxc_rnga_of_match); 198 199 static struct platform_driver mxc_rnga_driver = { 200 .driver = { 201 .name = "mxc_rnga", 202 .of_match_table = mxc_rnga_of_match, 203 }, 204 .remove = __exit_p(mxc_rnga_remove), 205 }; 206 207 module_platform_driver_probe(mxc_rnga_driver, mxc_rnga_probe); 208 209 MODULE_AUTHOR("Freescale Semiconductor, Inc."); 210 MODULE_DESCRIPTION("H/W RNGA driver for i.MX"); 211 MODULE_LICENSE("GPL"); 212