spmi-apple-controller.c

  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
 31struct 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
 39static 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 */
 45static 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
 61static 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
 93static 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
122static 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
151static const struct of_device_id apple_spmi_match_table[] = {
152	{ .compatible = "apple,t8103-spmi", },
153	{ .compatible = "apple,spmi", },
154	{}
155};
156MODULE_DEVICE_TABLE(of, apple_spmi_match_table);
157
158static struct platform_driver apple_spmi_driver = {
159	.probe		= apple_spmi_probe,
160	.driver		= {
161		.name	= "apple-spmi",
162		.of_match_table = apple_spmi_match_table,
163	},
164};
165module_platform_driver(apple_spmi_driver);
166
167MODULE_AUTHOR("Jean-Francois Bortolotti <jeff@borto.fr>");
168MODULE_DESCRIPTION("Apple SoC SPMI driver");
169MODULE_LICENSE("GPL");