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/io.h> 28 29 /* RNGA Registers */ 30 #define RNGA_CONTROL 0x00 31 #define RNGA_STATUS 0x04 32 #define RNGA_ENTROPY 0x08 33 #define RNGA_OUTPUT_FIFO 0x0c 34 #define RNGA_MODE 0x10 35 #define RNGA_VERIFICATION_CONTROL 0x14 36 #define RNGA_OSC_CONTROL_COUNTER 0x18 37 #define RNGA_OSC1_COUNTER 0x1c 38 #define RNGA_OSC2_COUNTER 0x20 39 #define RNGA_OSC_COUNTER_STATUS 0x24 40 41 /* RNGA Registers Range */ 42 #define RNG_ADDR_RANGE 0x28 43 44 /* RNGA Control Register */ 45 #define RNGA_CONTROL_SLEEP 0x00000010 46 #define RNGA_CONTROL_CLEAR_INT 0x00000008 47 #define RNGA_CONTROL_MASK_INTS 0x00000004 48 #define RNGA_CONTROL_HIGH_ASSURANCE 0x00000002 49 #define RNGA_CONTROL_GO 0x00000001 50 51 #define RNGA_STATUS_LEVEL_MASK 0x0000ff00 52 53 /* RNGA Status Register */ 54 #define RNGA_STATUS_OSC_DEAD 0x80000000 55 #define RNGA_STATUS_SLEEP 0x00000010 56 #define RNGA_STATUS_ERROR_INT 0x00000008 57 #define RNGA_STATUS_FIFO_UNDERFLOW 0x00000004 58 #define RNGA_STATUS_LAST_READ_STATUS 0x00000002 59 #define RNGA_STATUS_SECURITY_VIOLATION 0x00000001 60 61 static struct platform_device *rng_dev; 62 63 static int mxc_rnga_data_present(struct hwrng *rng) 64 { 65 int level; 66 void __iomem *rng_base = (void __iomem *)rng->priv; 67 68 /* how many random numbers is in FIFO? [0-16] */ 69 level = ((__raw_readl(rng_base + RNGA_STATUS) & 70 RNGA_STATUS_LEVEL_MASK) >> 8); 71 72 return level > 0 ? 1 : 0; 73 } 74 75 static int mxc_rnga_data_read(struct hwrng *rng, u32 * data) 76 { 77 int err; 78 u32 ctrl; 79 void __iomem *rng_base = (void __iomem *)rng->priv; 80 81 /* retrieve a random number from FIFO */ 82 *data = __raw_readl(rng_base + RNGA_OUTPUT_FIFO); 83 84 /* some error while reading this random number? */ 85 err = __raw_readl(rng_base + RNGA_STATUS) & RNGA_STATUS_ERROR_INT; 86 87 /* if error: clear error interrupt, but doesn't return random number */ 88 if (err) { 89 dev_dbg(&rng_dev->dev, "Error while reading random number!\n"); 90 ctrl = __raw_readl(rng_base + RNGA_CONTROL); 91 __raw_writel(ctrl | RNGA_CONTROL_CLEAR_INT, 92 rng_base + RNGA_CONTROL); 93 return 0; 94 } else 95 return 4; 96 } 97 98 static int mxc_rnga_init(struct hwrng *rng) 99 { 100 u32 ctrl, osc; 101 void __iomem *rng_base = (void __iomem *)rng->priv; 102 103 /* wake up */ 104 ctrl = __raw_readl(rng_base + RNGA_CONTROL); 105 __raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, rng_base + RNGA_CONTROL); 106 107 /* verify if oscillator is working */ 108 osc = __raw_readl(rng_base + RNGA_STATUS); 109 if (osc & RNGA_STATUS_OSC_DEAD) { 110 dev_err(&rng_dev->dev, "RNGA Oscillator is dead!\n"); 111 return -ENODEV; 112 } 113 114 /* go running */ 115 ctrl = __raw_readl(rng_base + RNGA_CONTROL); 116 __raw_writel(ctrl | RNGA_CONTROL_GO, rng_base + RNGA_CONTROL); 117 118 return 0; 119 } 120 121 static void mxc_rnga_cleanup(struct hwrng *rng) 122 { 123 u32 ctrl; 124 void __iomem *rng_base = (void __iomem *)rng->priv; 125 126 ctrl = __raw_readl(rng_base + RNGA_CONTROL); 127 128 /* stop rnga */ 129 __raw_writel(ctrl & ~RNGA_CONTROL_GO, rng_base + RNGA_CONTROL); 130 } 131 132 static struct hwrng mxc_rnga = { 133 .name = "mxc-rnga", 134 .init = mxc_rnga_init, 135 .cleanup = mxc_rnga_cleanup, 136 .data_present = mxc_rnga_data_present, 137 .data_read = mxc_rnga_data_read 138 }; 139 140 static int __init mxc_rnga_probe(struct platform_device *pdev) 141 { 142 int err = -ENODEV; 143 struct clk *clk; 144 struct resource *res, *mem; 145 void __iomem *rng_base = NULL; 146 147 if (rng_dev) 148 return -EBUSY; 149 150 clk = clk_get(&pdev->dev, "rng"); 151 if (IS_ERR(clk)) { 152 dev_err(&pdev->dev, "Could not get rng_clk!\n"); 153 err = PTR_ERR(clk); 154 goto out; 155 } 156 157 clk_enable(clk); 158 159 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 160 if (!res) { 161 err = -ENOENT; 162 goto err_region; 163 } 164 165 mem = request_mem_region(res->start, resource_size(res), pdev->name); 166 if (mem == NULL) { 167 err = -EBUSY; 168 goto err_region; 169 } 170 171 rng_base = ioremap(res->start, resource_size(res)); 172 if (!rng_base) { 173 err = -ENOMEM; 174 goto err_ioremap; 175 } 176 177 mxc_rnga.priv = (unsigned long)rng_base; 178 179 err = hwrng_register(&mxc_rnga); 180 if (err) { 181 dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err); 182 goto err_register; 183 } 184 185 rng_dev = pdev; 186 187 dev_info(&pdev->dev, "MXC RNGA Registered.\n"); 188 189 return 0; 190 191 err_register: 192 iounmap(rng_base); 193 rng_base = NULL; 194 195 err_ioremap: 196 release_mem_region(res->start, resource_size(res)); 197 198 err_region: 199 clk_disable(clk); 200 clk_put(clk); 201 202 out: 203 return err; 204 } 205 206 static int __exit mxc_rnga_remove(struct platform_device *pdev) 207 { 208 struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 209 void __iomem *rng_base = (void __iomem *)mxc_rnga.priv; 210 struct clk *clk = clk_get(&pdev->dev, "rng"); 211 212 hwrng_unregister(&mxc_rnga); 213 214 iounmap(rng_base); 215 216 release_mem_region(res->start, resource_size(res)); 217 218 clk_disable(clk); 219 clk_put(clk); 220 221 return 0; 222 } 223 224 static struct platform_driver mxc_rnga_driver = { 225 .driver = { 226 .name = "mxc_rnga", 227 .owner = THIS_MODULE, 228 }, 229 .remove = __exit_p(mxc_rnga_remove), 230 }; 231 232 static int __init mod_init(void) 233 { 234 return platform_driver_probe(&mxc_rnga_driver, mxc_rnga_probe); 235 } 236 237 static void __exit mod_exit(void) 238 { 239 platform_driver_unregister(&mxc_rnga_driver); 240 } 241 242 module_init(mod_init); 243 module_exit(mod_exit); 244 245 MODULE_AUTHOR("Freescale Semiconductor, Inc."); 246 MODULE_DESCRIPTION("H/W RNGA driver for i.MX"); 247 MODULE_LICENSE("GPL"); 248