summaryrefslogtreecommitdiffstats
path: root/drivers/soc/litex/litex_soc_ctrl.c
blob: 10813299aa1069c41033828297f400aadf17ccaa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
// SPDX-License-Identifier: GPL-2.0
/*
 * LiteX SoC Controller Driver
 *
 * Copyright (C) 2020 Antmicro <www.antmicro.com>
 *
 */

#include <linux/litex.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/reboot.h>

/* reset register located at the base address */
#define RESET_REG_OFF           0x00
#define RESET_REG_VALUE         0x00000001

#define SCRATCH_REG_OFF         0x04
#define SCRATCH_REG_VALUE       0x12345678
#define SCRATCH_TEST_VALUE      0xdeadbeef

/*
 * Check LiteX CSR read/write access
 *
 * This function reads and writes a scratch register in order to verify if CSR
 * access works.
 *
 * In case any problems are detected, the driver should panic.
 *
 * Access to the LiteX CSR is, by design, done in CPU native endianness.
 * The driver should not dynamically configure access functions when
 * the endianness mismatch is detected. Such situation indicates problems in
 * the soft SoC design and should be solved at the LiteX generator level,
 * not in the software.
 */
static int litex_check_csr_access(void __iomem *reg_addr)
{
	unsigned long reg;

	reg = litex_read32(reg_addr + SCRATCH_REG_OFF);

	if (reg != SCRATCH_REG_VALUE) {
		panic("Scratch register read error - the system is probably broken! Expected: 0x%x but got: 0x%lx",
			SCRATCH_REG_VALUE, reg);
		return -EINVAL;
	}

	litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_TEST_VALUE);
	reg = litex_read32(reg_addr + SCRATCH_REG_OFF);

	if (reg != SCRATCH_TEST_VALUE) {
		panic("Scratch register write error - the system is probably broken! Expected: 0x%x but got: 0x%lx",
			SCRATCH_TEST_VALUE, reg);
		return -EINVAL;
	}

	/* restore original value of the SCRATCH register */
	litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_REG_VALUE);

	pr_info("LiteX SoC Controller driver initialized");

	return 0;
}

struct litex_soc_ctrl_device {
	void __iomem *base;
	struct notifier_block reset_nb;
};

static int litex_reset_handler(struct notifier_block *this, unsigned long mode,
			       void *cmd)
{
	struct litex_soc_ctrl_device *soc_ctrl_dev =
		container_of(this, struct litex_soc_ctrl_device, reset_nb);

	litex_write32(soc_ctrl_dev->base + RESET_REG_OFF, RESET_REG_VALUE);
	return NOTIFY_DONE;
}

#ifdef CONFIG_OF
static const struct of_device_id litex_soc_ctrl_of_match[] = {
	{.compatible = "litex,soc-controller"},
	{},
};
MODULE_DEVICE_TABLE(of, litex_soc_ctrl_of_match);
#endif /* CONFIG_OF */

static int litex_soc_ctrl_probe(struct platform_device *pdev)
{
	struct litex_soc_ctrl_device *soc_ctrl_dev;
	int error;

	soc_ctrl_dev = devm_kzalloc(&pdev->dev, sizeof(*soc_ctrl_dev), GFP_KERNEL);
	if (!soc_ctrl_dev)
		return -ENOMEM;

	soc_ctrl_dev->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(soc_ctrl_dev->base))
		return PTR_ERR(soc_ctrl_dev->base);

	error = litex_check_csr_access(soc_ctrl_dev->base);
	if (error)
		return error;

	platform_set_drvdata(pdev, soc_ctrl_dev);

	soc_ctrl_dev->reset_nb.notifier_call = litex_reset_handler;
	soc_ctrl_dev->reset_nb.priority = 128;
	error = register_restart_handler(&soc_ctrl_dev->reset_nb);
	if (error) {
		dev_warn(&pdev->dev, "cannot register restart handler: %d\n",
			 error);
	}

	return 0;
}

static void litex_soc_ctrl_remove(struct platform_device *pdev)
{
	struct litex_soc_ctrl_device *soc_ctrl_dev = platform_get_drvdata(pdev);

	unregister_restart_handler(&soc_ctrl_dev->reset_nb);
}

static struct platform_driver litex_soc_ctrl_driver = {
	.driver = {
		.name = "litex-soc-controller",
		.of_match_table = of_match_ptr(litex_soc_ctrl_of_match)
	},
	.probe = litex_soc_ctrl_probe,
	.remove_new = litex_soc_ctrl_remove,
};

module_platform_driver(litex_soc_ctrl_driver);
MODULE_DESCRIPTION("LiteX SoC Controller driver");
MODULE_AUTHOR("Antmicro <www.antmicro.com>");
MODULE_LICENSE("GPL v2");