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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 <[email protected]>
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/platform_device.h>
18#include <linux/spmi.h>
19
20/* SPMI Controller Registers */
21#define SPMI_STATUS_REG 0
22#define SPMI_CMD_REG 0x4
23#define SPMI_RSP_REG 0x8
24
25#define SPMI_RX_FIFO_EMPTY BIT(24)
26
27#define REG_POLL_INTERVAL_US 10000
28#define REG_POLL_TIMEOUT_US (REG_POLL_INTERVAL_US * 5)
29
30struct apple_spmi {
31 void __iomem *regs;
32};
33
34#define poll_reg(spmi, reg, val, cond) \
35 readl_poll_timeout((spmi)->regs + (reg), (val), (cond), \
36 REG_POLL_INTERVAL_US, REG_POLL_TIMEOUT_US)
37
38static inline u32 apple_spmi_pack_cmd(u8 opc, u8 sid, u16 saddr, size_t len)
39{
40 return opc | sid << 8 | saddr << 16 | (len - 1) | (1 << 15);
41}
42
43/* Wait for Rx FIFO to have something */
44static int apple_spmi_wait_rx_not_empty(struct spmi_controller *ctrl)
45{
46 struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
47 int ret;
48 u32 status;
49
50 ret = poll_reg(spmi, SPMI_STATUS_REG, status, !(status & SPMI_RX_FIFO_EMPTY));
51 if (ret) {
52 dev_err(&ctrl->dev,
53 "failed to wait for RX FIFO not empty\n");
54 return ret;
55 }
56
57 return 0;
58}
59
60static int spmi_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
61 u16 saddr, u8 *buf, size_t len)
62{
63 struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
64 u32 spmi_cmd = apple_spmi_pack_cmd(opc, sid, saddr, len);
65 u32 rsp;
66 size_t len_read = 0;
67 u8 i;
68 int ret;
69
70 writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
71
72 ret = apple_spmi_wait_rx_not_empty(ctrl);
73 if (ret)
74 return ret;
75
76 /* Discard SPMI reply status */
77 readl(spmi->regs + SPMI_RSP_REG);
78
79 /* Read SPMI data reply */
80 while (len_read < len) {
81 rsp = readl(spmi->regs + SPMI_RSP_REG);
82 i = 0;
83 while ((len_read < len) && (i < 4)) {
84 buf[len_read++] = ((0xff << (8 * i)) & rsp) >> (8 * i);
85 i += 1;
86 }
87 }
88
89 return 0;
90}
91
92static int spmi_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
93 u16 saddr, const u8 *buf, size_t len)
94{
95 struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
96 u32 spmi_cmd = apple_spmi_pack_cmd(opc, sid, saddr, len);
97 size_t i = 0, j;
98 int ret;
99
100 writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
101
102 while (i < len) {
103 j = 0;
104 spmi_cmd = 0;
105 while ((j < 4) & (i < len))
106 spmi_cmd |= buf[i++] << (j++ * 8);
107
108 writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
109 }
110
111 ret = apple_spmi_wait_rx_not_empty(ctrl);
112 if (ret)
113 return ret;
114
115 /* Discard */
116 readl(spmi->regs + SPMI_RSP_REG);
117
118 return 0;
119}
120
121static int apple_spmi_probe(struct platform_device *pdev)
122{
123 struct apple_spmi *spmi;
124 struct spmi_controller *ctrl;
125 int ret;
126
127 ctrl = devm_spmi_controller_alloc(&pdev->dev, sizeof(*spmi));
128 if (IS_ERR(ctrl))
129 return -ENOMEM;
130
131 spmi = spmi_controller_get_drvdata(ctrl);
132
133 spmi->regs = devm_platform_ioremap_resource(pdev, 0);
134 if (IS_ERR(spmi->regs))
135 return PTR_ERR(spmi->regs);
136
137 ctrl->dev.of_node = pdev->dev.of_node;
138
139 ctrl->read_cmd = spmi_read_cmd;
140 ctrl->write_cmd = spmi_write_cmd;
141
142 ret = devm_spmi_controller_add(&pdev->dev, ctrl);
143 if (ret)
144 return dev_err_probe(&pdev->dev, ret,
145 "spmi_controller_add failed\n");
146
147 return 0;
148}
149
150static const struct of_device_id apple_spmi_match_table[] = {
151 { .compatible = "apple,t8103-spmi", },
152 { .compatible = "apple,spmi", },
153 {}
154};
155MODULE_DEVICE_TABLE(of, apple_spmi_match_table);
156
157static 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};
164module_platform_driver(apple_spmi_driver);
165
166MODULE_AUTHOR("Jean-Francois Bortolotti <[email protected]>");
167MODULE_DESCRIPTION("Apple SoC SPMI driver");
168MODULE_LICENSE("GPL");