1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Reset driver for the StarFive JH7100 SoC
4  *
5  * Copyright (C) 2021 Emil Renner Berthing <kernel@esmil.dk>
6  */
7 
8 #include <linux/mod_devicetable.h>
9 #include <linux/platform_device.h>
10 
11 #include "reset-starfive-jh71x0.h"
12 
13 #include <dt-bindings/reset/starfive-jh7100.h>
14 
15 /* register offsets */
16 #define JH7100_RESET_ASSERT0	0x00
17 #define JH7100_RESET_ASSERT1	0x04
18 #define JH7100_RESET_ASSERT2	0x08
19 #define JH7100_RESET_ASSERT3	0x0c
20 #define JH7100_RESET_STATUS0	0x10
21 #define JH7100_RESET_STATUS1	0x14
22 #define JH7100_RESET_STATUS2	0x18
23 #define JH7100_RESET_STATUS3	0x1c
24 
25 /*
26  * Writing a 1 to the n'th bit of the m'th ASSERT register asserts
27  * line 32m + n, and writing a 0 deasserts the same line.
28  * Most reset lines have their status inverted so a 0 bit in the STATUS
29  * register means the line is asserted and a 1 means it's deasserted. A few
30  * lines don't though, so store the expected value of the status registers when
31  * all lines are asserted.
32  */
33 static const u32 jh7100_reset_asserted[4] = {
34 	/* STATUS0 */
35 	BIT(JH7100_RST_U74 % 32) |
36 	BIT(JH7100_RST_VP6_DRESET % 32) |
37 	BIT(JH7100_RST_VP6_BRESET % 32),
38 	/* STATUS1 */
39 	BIT(JH7100_RST_HIFI4_DRESET % 32) |
40 	BIT(JH7100_RST_HIFI4_BRESET % 32),
41 	/* STATUS2 */
42 	BIT(JH7100_RST_E24 % 32),
43 	/* STATUS3 */
44 	0,
45 };
46 
jh7100_reset_probe(struct platform_device * pdev)47 static int __init jh7100_reset_probe(struct platform_device *pdev)
48 {
49 	void __iomem *base = devm_platform_ioremap_resource(pdev, 0);
50 
51 	if (IS_ERR(base))
52 		return PTR_ERR(base);
53 
54 	return reset_starfive_jh71x0_register(&pdev->dev, pdev->dev.of_node,
55 					      base + JH7100_RESET_ASSERT0,
56 					      base + JH7100_RESET_STATUS0,
57 					      jh7100_reset_asserted,
58 					      JH7100_RSTN_END,
59 					      THIS_MODULE);
60 }
61 
62 static const struct of_device_id jh7100_reset_dt_ids[] = {
63 	{ .compatible = "starfive,jh7100-reset" },
64 	{ /* sentinel */ }
65 };
66 
67 static struct platform_driver jh7100_reset_driver = {
68 	.driver = {
69 		.name = "jh7100-reset",
70 		.of_match_table = jh7100_reset_dt_ids,
71 		.suppress_bind_attrs = true,
72 	},
73 };
74 builtin_platform_driver_probe(jh7100_reset_driver, jh7100_reset_probe);
75