1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (c) 2013-2014, NVIDIA CORPORATION. All rights reserved. 4 * 5 * Based on drivers/misc/eeprom/sunxi_sid.c 6 */ 7 8 #include <linux/device.h> 9 #include <linux/clk.h> 10 #include <linux/completion.h> 11 #include <linux/dmaengine.h> 12 #include <linux/dma-mapping.h> 13 #include <linux/err.h> 14 #include <linux/io.h> 15 #include <linux/kernel.h> 16 #include <linux/kobject.h> 17 #include <linux/of_device.h> 18 #include <linux/platform_device.h> 19 #include <linux/random.h> 20 21 #include <soc/tegra/fuse.h> 22 23 #include "fuse.h" 24 25 #define FUSE_BEGIN 0x100 26 #define FUSE_UID_LOW 0x08 27 #define FUSE_UID_HIGH 0x0c 28 29 static u32 tegra20_fuse_read_early(struct tegra_fuse *fuse, unsigned int offset) 30 { 31 return readl_relaxed(fuse->base + FUSE_BEGIN + offset); 32 } 33 34 static void apb_dma_complete(void *args) 35 { 36 struct tegra_fuse *fuse = args; 37 38 complete(&fuse->apbdma.wait); 39 } 40 41 static u32 tegra20_fuse_read(struct tegra_fuse *fuse, unsigned int offset) 42 { 43 unsigned long flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK; 44 struct dma_async_tx_descriptor *dma_desc; 45 unsigned long time_left; 46 u32 value = 0; 47 int err; 48 49 mutex_lock(&fuse->apbdma.lock); 50 51 fuse->apbdma.config.src_addr = fuse->phys + FUSE_BEGIN + offset; 52 53 err = dmaengine_slave_config(fuse->apbdma.chan, &fuse->apbdma.config); 54 if (err) 55 goto out; 56 57 dma_desc = dmaengine_prep_slave_single(fuse->apbdma.chan, 58 fuse->apbdma.phys, 59 sizeof(u32), DMA_DEV_TO_MEM, 60 flags); 61 if (!dma_desc) 62 goto out; 63 64 dma_desc->callback = apb_dma_complete; 65 dma_desc->callback_param = fuse; 66 67 reinit_completion(&fuse->apbdma.wait); 68 69 clk_prepare_enable(fuse->clk); 70 71 dmaengine_submit(dma_desc); 72 dma_async_issue_pending(fuse->apbdma.chan); 73 time_left = wait_for_completion_timeout(&fuse->apbdma.wait, 74 msecs_to_jiffies(50)); 75 76 if (WARN(time_left == 0, "apb read dma timed out")) 77 dmaengine_terminate_all(fuse->apbdma.chan); 78 else 79 value = *fuse->apbdma.virt; 80 81 clk_disable_unprepare(fuse->clk); 82 83 out: 84 mutex_unlock(&fuse->apbdma.lock); 85 return value; 86 } 87 88 static bool dma_filter(struct dma_chan *chan, void *filter_param) 89 { 90 struct device_node *np = chan->device->dev->of_node; 91 92 return of_device_is_compatible(np, "nvidia,tegra20-apbdma"); 93 } 94 95 static int tegra20_fuse_probe(struct tegra_fuse *fuse) 96 { 97 dma_cap_mask_t mask; 98 99 dma_cap_zero(mask); 100 dma_cap_set(DMA_SLAVE, mask); 101 102 fuse->apbdma.chan = __dma_request_channel(&mask, dma_filter, NULL); 103 if (!fuse->apbdma.chan) 104 return -EPROBE_DEFER; 105 106 fuse->apbdma.virt = dma_alloc_coherent(fuse->dev, sizeof(u32), 107 &fuse->apbdma.phys, 108 GFP_KERNEL); 109 if (!fuse->apbdma.virt) { 110 dma_release_channel(fuse->apbdma.chan); 111 return -ENOMEM; 112 } 113 114 fuse->apbdma.config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES; 115 fuse->apbdma.config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES; 116 fuse->apbdma.config.src_maxburst = 1; 117 fuse->apbdma.config.dst_maxburst = 1; 118 fuse->apbdma.config.direction = DMA_DEV_TO_MEM; 119 fuse->apbdma.config.device_fc = false; 120 121 init_completion(&fuse->apbdma.wait); 122 mutex_init(&fuse->apbdma.lock); 123 fuse->read = tegra20_fuse_read; 124 125 return 0; 126 } 127 128 static const struct tegra_fuse_info tegra20_fuse_info = { 129 .read = tegra20_fuse_read, 130 .size = 0x1f8, 131 .spare = 0x100, 132 }; 133 134 /* Early boot code. This code is called before the devices are created */ 135 136 static void __init tegra20_fuse_add_randomness(void) 137 { 138 u32 randomness[7]; 139 140 randomness[0] = tegra_sku_info.sku_id; 141 randomness[1] = tegra_read_straps(); 142 randomness[2] = tegra_read_chipid(); 143 randomness[3] = tegra_sku_info.cpu_process_id << 16; 144 randomness[3] |= tegra_sku_info.soc_process_id; 145 randomness[4] = tegra_sku_info.cpu_speedo_id << 16; 146 randomness[4] |= tegra_sku_info.soc_speedo_id; 147 randomness[5] = tegra_fuse_read_early(FUSE_UID_LOW); 148 randomness[6] = tegra_fuse_read_early(FUSE_UID_HIGH); 149 150 add_device_randomness(randomness, sizeof(randomness)); 151 } 152 153 static void __init tegra20_fuse_init(struct tegra_fuse *fuse) 154 { 155 fuse->read_early = tegra20_fuse_read_early; 156 157 tegra_init_revision(); 158 fuse->soc->speedo_init(&tegra_sku_info); 159 tegra20_fuse_add_randomness(); 160 } 161 162 const struct tegra_fuse_soc tegra20_fuse_soc = { 163 .init = tegra20_fuse_init, 164 .speedo_init = tegra20_init_speedo_data, 165 .probe = tegra20_fuse_probe, 166 .info = &tegra20_fuse_info, 167 }; 168