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/pm_runtime.h>
20 #include <linux/random.h>
21 
22 #include <soc/tegra/fuse.h>
23 
24 #include "fuse.h"
25 
26 #define FUSE_BEGIN	0x100
27 #define FUSE_UID_LOW	0x08
28 #define FUSE_UID_HIGH	0x0c
29 
30 static u32 tegra20_fuse_read_early(struct tegra_fuse *fuse, unsigned int offset)
31 {
32 	return readl_relaxed(fuse->base + FUSE_BEGIN + offset);
33 }
34 
35 static void apb_dma_complete(void *args)
36 {
37 	struct tegra_fuse *fuse = args;
38 
39 	complete(&fuse->apbdma.wait);
40 }
41 
42 static u32 tegra20_fuse_read(struct tegra_fuse *fuse, unsigned int offset)
43 {
44 	unsigned long flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
45 	struct dma_async_tx_descriptor *dma_desc;
46 	unsigned long time_left;
47 	u32 value = 0;
48 	int err;
49 
50 	err = pm_runtime_resume_and_get(fuse->dev);
51 	if (err)
52 		return err;
53 
54 	mutex_lock(&fuse->apbdma.lock);
55 
56 	fuse->apbdma.config.src_addr = fuse->phys + FUSE_BEGIN + offset;
57 
58 	err = dmaengine_slave_config(fuse->apbdma.chan, &fuse->apbdma.config);
59 	if (err)
60 		goto out;
61 
62 	dma_desc = dmaengine_prep_slave_single(fuse->apbdma.chan,
63 					       fuse->apbdma.phys,
64 					       sizeof(u32), DMA_DEV_TO_MEM,
65 					       flags);
66 	if (!dma_desc)
67 		goto out;
68 
69 	dma_desc->callback = apb_dma_complete;
70 	dma_desc->callback_param = fuse;
71 
72 	reinit_completion(&fuse->apbdma.wait);
73 
74 	dmaengine_submit(dma_desc);
75 	dma_async_issue_pending(fuse->apbdma.chan);
76 	time_left = wait_for_completion_timeout(&fuse->apbdma.wait,
77 						msecs_to_jiffies(50));
78 
79 	if (WARN(time_left == 0, "apb read dma timed out"))
80 		dmaengine_terminate_all(fuse->apbdma.chan);
81 	else
82 		value = *fuse->apbdma.virt;
83 
84 out:
85 	mutex_unlock(&fuse->apbdma.lock);
86 	pm_runtime_put(fuse->dev);
87 	return value;
88 }
89 
90 static bool dma_filter(struct dma_chan *chan, void *filter_param)
91 {
92 	struct device_node *np = chan->device->dev->of_node;
93 
94 	return of_device_is_compatible(np, "nvidia,tegra20-apbdma");
95 }
96 
97 static int tegra20_fuse_probe(struct tegra_fuse *fuse)
98 {
99 	dma_cap_mask_t mask;
100 
101 	dma_cap_zero(mask);
102 	dma_cap_set(DMA_SLAVE, mask);
103 
104 	fuse->apbdma.chan = dma_request_channel(mask, dma_filter, NULL);
105 	if (!fuse->apbdma.chan)
106 		return -EPROBE_DEFER;
107 
108 	fuse->apbdma.virt = dma_alloc_coherent(fuse->dev, sizeof(u32),
109 					       &fuse->apbdma.phys,
110 					       GFP_KERNEL);
111 	if (!fuse->apbdma.virt) {
112 		dma_release_channel(fuse->apbdma.chan);
113 		return -ENOMEM;
114 	}
115 
116 	fuse->apbdma.config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
117 	fuse->apbdma.config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
118 	fuse->apbdma.config.src_maxburst = 1;
119 	fuse->apbdma.config.dst_maxburst = 1;
120 	fuse->apbdma.config.direction = DMA_DEV_TO_MEM;
121 	fuse->apbdma.config.device_fc = false;
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 	.soc_attr_group = &tegra_soc_attr_group,
170 	.clk_suspend_on = false,
171 };
172