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