kernel/drivers/soc/tegra/fuse/fuse-tegra20.c

   1 /*
   2  * Copyright (c) 2013-2014, NVIDIA CORPORATION.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15  *
  16  * Based on drivers/misc/eeprom/sunxi_sid.c
  17  */
  18
  19 #include <linux/device.h>
  20 #include <linux/clk.h>
  21 #include <linux/completion.h>
  22 #include <linux/dmaengine.h>
  23 #include <linux/dma-mapping.h>
  24 #include <linux/err.h>
  25 #include <linux/io.h>
  26 #include <linux/kernel.h>
  27 #include <linux/kobject.h>
  28 #include <linux/of_device.h>
  29 #include <linux/platform_device.h>
  30 #include <linux/random.h>
  31
  32 #include <soc/tegra/fuse.h>
  33
  34 #include "fuse.h"
  35
  36 #define FUSE_BEGIN      0x100
  37 #define FUSE_UID_LOW    0x08
  38 #define FUSE_UID_HIGH   0x0c
  39
  40 static u32 tegra20_fuse_read_early(struct tegra_fuse *fuse, unsigned int offset)
  41 {
  42         return readl_relaxed(fuse->base + FUSE_BEGIN + offset);
  43 }
  44
  45 static void apb_dma_complete(void *args)
  46 {
  47         struct tegra_fuse *fuse = args;
  48
  49         complete(&fuse->apbdma.wait);
  50 }
  51
  52 static u32 tegra20_fuse_read(struct tegra_fuse *fuse, unsigned int offset)
  53 {
  54         unsigned long flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
  55         struct dma_async_tx_descriptor *dma_desc;
  56         unsigned long time_left;
  57         u32 value = 0;
  58         int err;
  59
  60         mutex_lock(&fuse->apbdma.lock);
  61
  62         fuse->apbdma.config.src_addr = fuse->apbdma.phys + FUSE_BEGIN + offset;
  63
  64         err = dmaengine_slave_config(fuse->apbdma.chan, &fuse->apbdma.config);
  65         if (err)
  66                 goto out;
  67
  68         dma_desc = dmaengine_prep_slave_single(fuse->apbdma.chan,
  69                                                fuse->apbdma.phys,
  70                                                sizeof(u32), DMA_DEV_TO_MEM,
  71                                                flags);
  72         if (!dma_desc)
  73                 goto out;
  74
  75         dma_desc->callback = apb_dma_complete;
  76         dma_desc->callback_param = fuse;
  77
  78         reinit_completion(&fuse->apbdma.wait);
  79
  80         clk_prepare_enable(fuse->clk);
  81
  82         dmaengine_submit(dma_desc);
  83         dma_async_issue_pending(fuse->apbdma.chan);
  84         time_left = wait_for_completion_timeout(&fuse->apbdma.wait,
  85                                                 msecs_to_jiffies(50));
  86
  87         if (WARN(time_left == 0, "apb read dma timed out"))
  88                 dmaengine_terminate_all(fuse->apbdma.chan);
  89         else
  90                 value = *fuse->apbdma.virt;
  91
  92         clk_disable_unprepare(fuse->clk);
  93
  94 out:
  95         mutex_unlock(&fuse->apbdma.lock);
  96         return value;
  97 }
  98
  99 static int tegra20_fuse_probe(struct tegra_fuse *fuse)
 100 {
 101         dma_cap_mask_t mask;
 102
 103         dma_cap_zero(mask);
 104         dma_cap_set(DMA_SLAVE, mask);
 105
 106         fuse->apbdma.chan = dma_request_channel(mask, NULL, NULL);
 107         if (!fuse->apbdma.chan)
 108                 return -EPROBE_DEFER;
 109
 110         fuse->apbdma.virt = dma_alloc_coherent(fuse->dev, sizeof(u32),
 111                                                &fuse->apbdma.phys,
 112                                                GFP_KERNEL);
 113         if (!fuse->apbdma.virt) {
 114                 dma_release_channel(fuse->apbdma.chan);
 115                 return -ENOMEM;
 116         }
 117
 118         fuse->apbdma.config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 119         fuse->apbdma.config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 120         fuse->apbdma.config.src_maxburst = 1;
 121         fuse->apbdma.config.dst_maxburst = 1;
 122
 123         init_completion(&fuse->apbdma.wait);
 124         mutex_init(&fuse->apbdma.lock);
 125         fuse->read = tegra20_fuse_read;
 126
 127         return 0;
 128 }
 129
 130 static const struct tegra_fuse_info tegra20_fuse_info = {
 131         .read = tegra20_fuse_read,
 132         .size = 0x1f8,
 133         .spare = 0x100,
 134 };
 135
 136 /* Early boot code. This code is called before the devices are created */
 137
 138 static void __init tegra20_fuse_add_randomness(void)
 139 {
 140         u32 randomness[7];
 141
 142         randomness[0] = tegra_sku_info.sku_id;
 143         randomness[1] = tegra_read_straps();
 144         randomness[2] = tegra_read_chipid();
 145         randomness[3] = tegra_sku_info.cpu_process_id << 16;
 146         randomness[3] |= tegra_sku_info.soc_process_id;
 147         randomness[4] = tegra_sku_info.cpu_speedo_id << 16;
 148         randomness[4] |= tegra_sku_info.soc_speedo_id;
 149         randomness[5] = tegra_fuse_read_early(FUSE_UID_LOW);
 150         randomness[6] = tegra_fuse_read_early(FUSE_UID_HIGH);
 151
 152         add_device_randomness(randomness, sizeof(randomness));
 153 }
 154
 155 static void __init tegra20_fuse_init(struct tegra_fuse *fuse)
 156 {
 157         fuse->read_early = tegra20_fuse_read_early;
 158
 159         tegra_init_revision();
 160         fuse->soc->speedo_init(&tegra_sku_info);
 161         tegra20_fuse_add_randomness();
 162 }
 163
 164 const struct tegra_fuse_soc tegra20_fuse_soc = {
 165         .init = tegra20_fuse_init,
 166         .speedo_init = tegra20_init_speedo_data,
 167         .probe = tegra20_fuse_probe,
 168         .info = &tegra20_fuse_info,
 169 };