Stanimir Varbanov | 0d28978 | 2013-10-15 17:11:18 +0300 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2011-2013, The Linux Foundation. All rights reserved. |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 and |
| 6 | * only version 2 as published by the Free Software Foundation. |
| 7 | * |
| 8 | * This program is distributed in the hope that it will be useful, |
| 9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 11 | * GNU General Public License for more details. |
| 12 | * |
| 13 | */ |
| 14 | #include <linux/clk.h> |
| 15 | #include <linux/err.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 | /* Device specific register offsets */ |
| 23 | #define PRNG_DATA_OUT 0x0000 |
| 24 | #define PRNG_STATUS 0x0004 |
| 25 | #define PRNG_LFSR_CFG 0x0100 |
| 26 | #define PRNG_CONFIG 0x0104 |
| 27 | |
| 28 | /* Device specific register masks and config values */ |
| 29 | #define PRNG_LFSR_CFG_MASK 0x0000ffff |
| 30 | #define PRNG_LFSR_CFG_CLOCKS 0x0000dddd |
| 31 | #define PRNG_CONFIG_HW_ENABLE BIT(1) |
| 32 | #define PRNG_STATUS_DATA_AVAIL BIT(0) |
| 33 | |
| 34 | #define MAX_HW_FIFO_DEPTH 16 |
| 35 | #define MAX_HW_FIFO_SIZE (MAX_HW_FIFO_DEPTH * 4) |
| 36 | #define WORD_SZ 4 |
| 37 | |
| 38 | struct msm_rng { |
| 39 | void __iomem *base; |
| 40 | struct clk *clk; |
| 41 | struct hwrng hwrng; |
| 42 | }; |
| 43 | |
| 44 | #define to_msm_rng(p) container_of(p, struct msm_rng, hwrng) |
| 45 | |
| 46 | static int msm_rng_enable(struct hwrng *hwrng, int enable) |
| 47 | { |
| 48 | struct msm_rng *rng = to_msm_rng(hwrng); |
| 49 | u32 val; |
| 50 | int ret; |
| 51 | |
| 52 | ret = clk_prepare_enable(rng->clk); |
| 53 | if (ret) |
| 54 | return ret; |
| 55 | |
| 56 | if (enable) { |
| 57 | /* Enable PRNG only if it is not already enabled */ |
| 58 | val = readl_relaxed(rng->base + PRNG_CONFIG); |
| 59 | if (val & PRNG_CONFIG_HW_ENABLE) |
| 60 | goto already_enabled; |
| 61 | |
| 62 | val = readl_relaxed(rng->base + PRNG_LFSR_CFG); |
| 63 | val &= ~PRNG_LFSR_CFG_MASK; |
| 64 | val |= PRNG_LFSR_CFG_CLOCKS; |
| 65 | writel(val, rng->base + PRNG_LFSR_CFG); |
| 66 | |
| 67 | val = readl_relaxed(rng->base + PRNG_CONFIG); |
| 68 | val |= PRNG_CONFIG_HW_ENABLE; |
| 69 | writel(val, rng->base + PRNG_CONFIG); |
| 70 | } else { |
| 71 | val = readl_relaxed(rng->base + PRNG_CONFIG); |
| 72 | val &= ~PRNG_CONFIG_HW_ENABLE; |
| 73 | writel(val, rng->base + PRNG_CONFIG); |
| 74 | } |
| 75 | |
| 76 | already_enabled: |
| 77 | clk_disable_unprepare(rng->clk); |
| 78 | return 0; |
| 79 | } |
| 80 | |
| 81 | static int msm_rng_read(struct hwrng *hwrng, void *data, size_t max, bool wait) |
| 82 | { |
| 83 | struct msm_rng *rng = to_msm_rng(hwrng); |
| 84 | size_t currsize = 0; |
| 85 | u32 *retdata = data; |
| 86 | size_t maxsize; |
| 87 | int ret; |
| 88 | u32 val; |
| 89 | |
| 90 | /* calculate max size bytes to transfer back to caller */ |
| 91 | maxsize = min_t(size_t, MAX_HW_FIFO_SIZE, max); |
| 92 | |
| 93 | /* no room for word data */ |
| 94 | if (maxsize < WORD_SZ) |
| 95 | return 0; |
| 96 | |
| 97 | ret = clk_prepare_enable(rng->clk); |
| 98 | if (ret) |
| 99 | return ret; |
| 100 | |
| 101 | /* read random data from hardware */ |
| 102 | do { |
| 103 | val = readl_relaxed(rng->base + PRNG_STATUS); |
| 104 | if (!(val & PRNG_STATUS_DATA_AVAIL)) |
| 105 | break; |
| 106 | |
| 107 | val = readl_relaxed(rng->base + PRNG_DATA_OUT); |
| 108 | if (!val) |
| 109 | break; |
| 110 | |
| 111 | *retdata++ = val; |
| 112 | currsize += WORD_SZ; |
| 113 | |
| 114 | /* make sure we stay on 32bit boundary */ |
| 115 | if ((maxsize - currsize) < WORD_SZ) |
| 116 | break; |
| 117 | } while (currsize < maxsize); |
| 118 | |
| 119 | clk_disable_unprepare(rng->clk); |
| 120 | |
| 121 | return currsize; |
| 122 | } |
| 123 | |
| 124 | static int msm_rng_init(struct hwrng *hwrng) |
| 125 | { |
| 126 | return msm_rng_enable(hwrng, 1); |
| 127 | } |
| 128 | |
| 129 | static void msm_rng_cleanup(struct hwrng *hwrng) |
| 130 | { |
| 131 | msm_rng_enable(hwrng, 0); |
| 132 | } |
| 133 | |
| 134 | static int msm_rng_probe(struct platform_device *pdev) |
| 135 | { |
| 136 | struct resource *res; |
| 137 | struct msm_rng *rng; |
| 138 | int ret; |
| 139 | |
| 140 | rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL); |
| 141 | if (!rng) |
| 142 | return -ENOMEM; |
| 143 | |
| 144 | platform_set_drvdata(pdev, rng); |
| 145 | |
| 146 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
| 147 | rng->base = devm_ioremap_resource(&pdev->dev, res); |
| 148 | if (IS_ERR(rng->base)) |
| 149 | return PTR_ERR(rng->base); |
| 150 | |
| 151 | rng->clk = devm_clk_get(&pdev->dev, "core"); |
| 152 | if (IS_ERR(rng->clk)) |
| 153 | return PTR_ERR(rng->clk); |
| 154 | |
| 155 | rng->hwrng.name = KBUILD_MODNAME, |
| 156 | rng->hwrng.init = msm_rng_init, |
| 157 | rng->hwrng.cleanup = msm_rng_cleanup, |
| 158 | rng->hwrng.read = msm_rng_read, |
| 159 | |
Dmitry Torokhov | 9052b0d | 2015-03-12 14:00:05 -0700 | [diff] [blame^] | 160 | ret = devm_hwrng_register(&pdev->dev, &rng->hwrng); |
Stanimir Varbanov | 0d28978 | 2013-10-15 17:11:18 +0300 | [diff] [blame] | 161 | if (ret) { |
| 162 | dev_err(&pdev->dev, "failed to register hwrng\n"); |
| 163 | return ret; |
| 164 | } |
| 165 | |
| 166 | return 0; |
| 167 | } |
| 168 | |
Stanimir Varbanov | 0d28978 | 2013-10-15 17:11:18 +0300 | [diff] [blame] | 169 | static const struct of_device_id msm_rng_of_match[] = { |
| 170 | { .compatible = "qcom,prng", }, |
| 171 | {} |
| 172 | }; |
| 173 | MODULE_DEVICE_TABLE(of, msm_rng_of_match); |
| 174 | |
| 175 | static struct platform_driver msm_rng_driver = { |
| 176 | .probe = msm_rng_probe, |
Stanimir Varbanov | 0d28978 | 2013-10-15 17:11:18 +0300 | [diff] [blame] | 177 | .driver = { |
| 178 | .name = KBUILD_MODNAME, |
Stanimir Varbanov | 0d28978 | 2013-10-15 17:11:18 +0300 | [diff] [blame] | 179 | .of_match_table = of_match_ptr(msm_rng_of_match), |
| 180 | } |
| 181 | }; |
| 182 | module_platform_driver(msm_rng_driver); |
| 183 | |
| 184 | MODULE_ALIAS("platform:" KBUILD_MODNAME); |
| 185 | MODULE_AUTHOR("The Linux Foundation"); |
| 186 | MODULE_DESCRIPTION("Qualcomm MSM random number generator driver"); |
| 187 | MODULE_LICENSE("GPL v2"); |