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