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