tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * LiteX SoC Controller Driver
4 *
5 * Copyright (C) 2020 Antmicro <www.antmicro.com>
6 *
7 */
8
9#include <linux/litex.h>
10#include <linux/device.h>
11#include <linux/errno.h>
12#include <linux/of.h>
13#include <linux/platform_device.h>
14#include <linux/printk.h>
15#include <linux/module.h>
16#include <linux/errno.h>
17#include <linux/io.h>
18#include <linux/reboot.h>
19
20/* reset register located at the base address */
21#define RESET_REG_OFF 0x00
22#define RESET_REG_VALUE 0x00000001
23
24#define SCRATCH_REG_OFF 0x04
25#define SCRATCH_REG_VALUE 0x12345678
26#define SCRATCH_TEST_VALUE 0xdeadbeef
27
28/*
29 * Check LiteX CSR read/write access
30 *
31 * This function reads and writes a scratch register in order to verify if CSR
32 * access works.
33 *
34 * In case any problems are detected, the driver should panic.
35 *
36 * Access to the LiteX CSR is, by design, done in CPU native endianness.
37 * The driver should not dynamically configure access functions when
38 * the endianness mismatch is detected. Such situation indicates problems in
39 * the soft SoC design and should be solved at the LiteX generator level,
40 * not in the software.
41 */
42static int litex_check_csr_access(void __iomem *reg_addr)
43{
44 unsigned long reg;
45
46 reg = litex_read32(reg_addr + SCRATCH_REG_OFF);
47
48 if (reg != SCRATCH_REG_VALUE) {
49 panic("Scratch register read error - the system is probably broken! Expected: 0x%x but got: 0x%lx",
50 SCRATCH_REG_VALUE, reg);
51 return -EINVAL;
52 }
53
54 litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_TEST_VALUE);
55 reg = litex_read32(reg_addr + SCRATCH_REG_OFF);
56
57 if (reg != SCRATCH_TEST_VALUE) {
58 panic("Scratch register write error - the system is probably broken! Expected: 0x%x but got: 0x%lx",
59 SCRATCH_TEST_VALUE, reg);
60 return -EINVAL;
61 }
62
63 /* restore original value of the SCRATCH register */
64 litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_REG_VALUE);
65
66 pr_info("LiteX SoC Controller driver initialized: subreg:%d, align:%d",
67 LITEX_SUBREG_SIZE, LITEX_SUBREG_ALIGN);
68
69 return 0;
70}
71
72struct litex_soc_ctrl_device {
73 void __iomem *base;
74 struct notifier_block reset_nb;
75};
76
77static int litex_reset_handler(struct notifier_block *this, unsigned long mode,
78 void *cmd)
79{
80 struct litex_soc_ctrl_device *soc_ctrl_dev =
81 container_of(this, struct litex_soc_ctrl_device, reset_nb);
82
83 litex_write32(soc_ctrl_dev->base + RESET_REG_OFF, RESET_REG_VALUE);
84 return NOTIFY_DONE;
85}
86
87#ifdef CONFIG_OF
88static const struct of_device_id litex_soc_ctrl_of_match[] = {
89 {.compatible = "litex,soc-controller"},
90 {},
91};
92MODULE_DEVICE_TABLE(of, litex_soc_ctrl_of_match);
93#endif /* CONFIG_OF */
94
95static int litex_soc_ctrl_probe(struct platform_device *pdev)
96{
97 struct litex_soc_ctrl_device *soc_ctrl_dev;
98 int error;
99
100 soc_ctrl_dev = devm_kzalloc(&pdev->dev, sizeof(*soc_ctrl_dev), GFP_KERNEL);
101 if (!soc_ctrl_dev)
102 return -ENOMEM;
103
104 soc_ctrl_dev->base = devm_platform_ioremap_resource(pdev, 0);
105 if (IS_ERR(soc_ctrl_dev->base))
106 return PTR_ERR(soc_ctrl_dev->base);
107
108 error = litex_check_csr_access(soc_ctrl_dev->base);
109 if (error)
110 return error;
111
112 platform_set_drvdata(pdev, soc_ctrl_dev);
113
114 soc_ctrl_dev->reset_nb.notifier_call = litex_reset_handler;
115 soc_ctrl_dev->reset_nb.priority = 128;
116 error = register_restart_handler(&soc_ctrl_dev->reset_nb);
117 if (error) {
118 dev_warn(&pdev->dev, "cannot register restart handler: %d\n",
119 error);
120 }
121
122 return 0;
123}
124
125static int litex_soc_ctrl_remove(struct platform_device *pdev)
126{
127 struct litex_soc_ctrl_device *soc_ctrl_dev = platform_get_drvdata(pdev);
128
129 unregister_restart_handler(&soc_ctrl_dev->reset_nb);
130 return 0;
131}
132
133static struct platform_driver litex_soc_ctrl_driver = {
134 .driver = {
135 .name = "litex-soc-controller",
136 .of_match_table = of_match_ptr(litex_soc_ctrl_of_match)
137 },
138 .probe = litex_soc_ctrl_probe,
139 .remove = litex_soc_ctrl_remove,
140};
141
142module_platform_driver(litex_soc_ctrl_driver);
143MODULE_DESCRIPTION("LiteX SoC Controller driver");
144MODULE_AUTHOR("Antmicro <www.antmicro.com>");
145MODULE_LICENSE("GPL v2");