1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Apple SoC SPMI device driver
4  *
5  * Copyright The Asahi Linux Contributors
6  *
7  * Inspired by:
8  *		OpenBSD support Copyright (c) 2021 Mark Kettenis <kettenis@openbsd.org>
9  *		Correllium support Copyright (C) 2021 Corellium LLC
10  *		hisi-spmi-controller.c
11  *		spmi-pmic-arb.c Copyright (c) 2021, The Linux Foundation.
12  */
13 
14 #include <linux/io.h>
15 #include <linux/iopoll.h>
16 #include <linux/module.h>
17 #include <linux/mod_devicetable.h>
18 #include <linux/platform_device.h>
19 #include <linux/spmi.h>
20 
21 /* SPMI Controller Registers */
22 #define SPMI_STATUS_REG 0
23 #define SPMI_CMD_REG 0x4
24 #define SPMI_RSP_REG 0x8
25 
26 #define SPMI_RX_FIFO_EMPTY BIT(24)
27 
28 #define REG_POLL_INTERVAL_US 10000
29 #define REG_POLL_TIMEOUT_US (REG_POLL_INTERVAL_US * 5)
30 
31 struct apple_spmi {
32 	void __iomem *regs;
33 };
34 
35 #define poll_reg(spmi, reg, val, cond) \
36 	readl_poll_timeout((spmi)->regs + (reg), (val), (cond), \
37 			   REG_POLL_INTERVAL_US, REG_POLL_TIMEOUT_US)
38 
39 static inline u32 apple_spmi_pack_cmd(u8 opc, u8 sid, u16 saddr, size_t len)
40 {
41 	return opc | sid << 8 | saddr << 16 | (len - 1) | (1 << 15);
42 }
43 
44 /* Wait for Rx FIFO to have something */
45 static int apple_spmi_wait_rx_not_empty(struct spmi_controller *ctrl)
46 {
47 	struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
48 	int ret;
49 	u32 status;
50 
51 	ret = poll_reg(spmi, SPMI_STATUS_REG, status, !(status & SPMI_RX_FIFO_EMPTY));
52 	if (ret) {
53 		dev_err(&ctrl->dev,
54 			"failed to wait for RX FIFO not empty\n");
55 		return ret;
56 	}
57 
58 	return 0;
59 }
60 
61 static int spmi_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
62 			 u16 saddr, u8 *buf, size_t len)
63 {
64 	struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
65 	u32 spmi_cmd = apple_spmi_pack_cmd(opc, sid, saddr, len);
66 	u32 rsp;
67 	size_t len_read = 0;
68 	u8 i;
69 	int ret;
70 
71 	writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
72 
73 	ret = apple_spmi_wait_rx_not_empty(ctrl);
74 	if (ret)
75 		return ret;
76 
77 	/* Discard SPMI reply status */
78 	readl(spmi->regs + SPMI_RSP_REG);
79 
80 	/* Read SPMI data reply */
81 	while (len_read < len) {
82 		rsp = readl(spmi->regs + SPMI_RSP_REG);
83 		i = 0;
84 		while ((len_read < len) && (i < 4)) {
85 			buf[len_read++] = ((0xff << (8 * i)) & rsp) >> (8 * i);
86 			i += 1;
87 		}
88 	}
89 
90 	return 0;
91 }
92 
93 static int spmi_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
94 			  u16 saddr, const u8 *buf, size_t len)
95 {
96 	struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
97 	u32 spmi_cmd = apple_spmi_pack_cmd(opc, sid, saddr, len);
98 	size_t i = 0, j;
99 	int ret;
100 
101 	writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
102 
103 	while (i < len) {
104 		j = 0;
105 		spmi_cmd = 0;
106 		while ((j < 4) & (i < len))
107 			spmi_cmd |= buf[i++] << (j++ * 8);
108 
109 		writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
110 	}
111 
112 	ret = apple_spmi_wait_rx_not_empty(ctrl);
113 	if (ret)
114 		return ret;
115 
116 	/* Discard */
117 	readl(spmi->regs + SPMI_RSP_REG);
118 
119 	return 0;
120 }
121 
122 static int apple_spmi_probe(struct platform_device *pdev)
123 {
124 	struct apple_spmi *spmi;
125 	struct spmi_controller *ctrl;
126 	int ret;
127 
128 	ctrl = devm_spmi_controller_alloc(&pdev->dev, sizeof(*spmi));
129 	if (IS_ERR(ctrl))
130 		return -ENOMEM;
131 
132 	spmi = spmi_controller_get_drvdata(ctrl);
133 
134 	spmi->regs = devm_platform_ioremap_resource(pdev, 0);
135 	if (IS_ERR(spmi->regs))
136 		return PTR_ERR(spmi->regs);
137 
138 	ctrl->dev.of_node = pdev->dev.of_node;
139 
140 	ctrl->read_cmd = spmi_read_cmd;
141 	ctrl->write_cmd = spmi_write_cmd;
142 
143 	ret = devm_spmi_controller_add(&pdev->dev, ctrl);
144 	if (ret)
145 		return dev_err_probe(&pdev->dev, ret,
146 				     "spmi_controller_add failed\n");
147 
148 	return 0;
149 }
150 
151 static const struct of_device_id apple_spmi_match_table[] = {
152 	{ .compatible = "apple,spmi", },
153 	{}
154 };
155 MODULE_DEVICE_TABLE(of, apple_spmi_match_table);
156 
157 static struct platform_driver apple_spmi_driver = {
158 	.probe		= apple_spmi_probe,
159 	.driver		= {
160 		.name	= "apple-spmi",
161 		.of_match_table = apple_spmi_match_table,
162 	},
163 };
164 module_platform_driver(apple_spmi_driver);
165 
166 MODULE_AUTHOR("Jean-Francois Bortolotti <jeff@borto.fr>");
167 MODULE_DESCRIPTION("Apple SoC SPMI driver");
168 MODULE_LICENSE("GPL");
169