1// SPDX-License-Identifier: GPL-2.0
2/*
3 * StarFive Designware Mobile Storage Host Controller Driver
4 *
5 * Copyright (c) 2022 StarFive Technology Co., Ltd.
6 */
7
8#include <linux/clk.h>
9#include <linux/delay.h>
10#include <linux/mfd/syscon.h>
11#include <linux/mmc/host.h>
12#include <linux/module.h>
13#include <linux/of_address.h>
14#include <linux/platform_device.h>
15#include <linux/regmap.h>
16
17#include "dw_mmc.h"
18#include "dw_mmc-pltfm.h"
19
20#define ALL_INT_CLR		0x1ffff
21#define MAX_DELAY_CHAIN		32
22
23struct starfive_priv {
24	struct device *dev;
25	struct regmap *reg_syscon;
26	u32 syscon_offset;
27	u32 syscon_shift;
28	u32 syscon_mask;
29};
30
31static void dw_mci_starfive_set_ios(struct dw_mci *host, struct mmc_ios *ios)
32{
33	int ret;
34	unsigned int clock;
35
36	if (ios->timing == MMC_TIMING_MMC_DDR52 || ios->timing == MMC_TIMING_UHS_DDR50) {
37		clock = (ios->clock > 50000000 && ios->clock <= 52000000) ? 100000000 : ios->clock;
38		ret = clk_set_rate(host->ciu_clk, clock);
39		if (ret)
40			dev_dbg(host->dev, "Use an external frequency divider %uHz\n", ios->clock);
41		host->bus_hz = clk_get_rate(host->ciu_clk);
42	} else {
43		dev_dbg(host->dev, "Using the internal divider\n");
44	}
45}
46
47static int dw_mci_starfive_execute_tuning(struct dw_mci_slot *slot,
48					     u32 opcode)
49{
50	static const int grade  = MAX_DELAY_CHAIN;
51	struct dw_mci *host = slot->host;
52	struct starfive_priv *priv = host->priv;
53	int rise_point = -1, fall_point = -1;
54	int err, prev_err = 0;
55	int i;
56	bool found = 0;
57	u32 regval;
58
59	/*
60	 * Use grade as the max delay chain, and use the rise_point and
61	 * fall_point to ensure the best sampling point of a data input
62	 * signals.
63	 */
64	for (i = 0; i < grade; i++) {
65		regval = i << priv->syscon_shift;
66		err = regmap_update_bits(priv->reg_syscon, priv->syscon_offset,
67						priv->syscon_mask, regval);
68		if (err)
69			return err;
70		mci_writel(host, RINTSTS, ALL_INT_CLR);
71
72		err = mmc_send_tuning(slot->mmc, opcode, NULL);
73		if (!err)
74			found = 1;
75
76		if (i > 0) {
77			if (err && !prev_err)
78				fall_point = i - 1;
79			if (!err && prev_err)
80				rise_point = i;
81		}
82
83		if (rise_point != -1 && fall_point != -1)
84			goto tuning_out;
85
86		prev_err = err;
87		err = 0;
88	}
89
90tuning_out:
91	if (found) {
92		if (rise_point == -1)
93			rise_point = 0;
94		if (fall_point == -1)
95			fall_point = grade - 1;
96		if (fall_point < rise_point) {
97			if ((rise_point + fall_point) >
98			    (grade - 1))
99				i = fall_point / 2;
100			else
101				i = (rise_point + grade - 1) / 2;
102		} else {
103			i = (rise_point + fall_point) / 2;
104		}
105
106		regval = i << priv->syscon_shift;
107		err = regmap_update_bits(priv->reg_syscon, priv->syscon_offset,
108						priv->syscon_mask, regval);
109		if (err)
110			return err;
111		mci_writel(host, RINTSTS, ALL_INT_CLR);
112
113		dev_info(host->dev, "Found valid delay chain! use it [delay=%d]\n", i);
114	} else {
115		dev_err(host->dev, "No valid delay chain! use default\n");
116		err = -EINVAL;
117	}
118
119	mci_writel(host, RINTSTS, ALL_INT_CLR);
120	return err;
121}
122
123static int dw_mci_starfive_parse_dt(struct dw_mci *host)
124{
125	struct of_phandle_args args;
126	struct starfive_priv *priv;
127	int ret;
128
129	priv = devm_kzalloc(host->dev, sizeof(*priv), GFP_KERNEL);
130	if (!priv)
131		return -ENOMEM;
132
133	ret = of_parse_phandle_with_fixed_args(host->dev->of_node,
134						"starfive,sysreg", 3, 0, &args);
135	if (ret) {
136		dev_err(host->dev, "Failed to parse starfive,sysreg\n");
137		return -EINVAL;
138	}
139
140	priv->reg_syscon = syscon_node_to_regmap(args.np);
141	of_node_put(args.np);
142	if (IS_ERR(priv->reg_syscon))
143		return PTR_ERR(priv->reg_syscon);
144
145	priv->syscon_offset = args.args[0];
146	priv->syscon_shift  = args.args[1];
147	priv->syscon_mask   = args.args[2];
148
149	host->priv = priv;
150
151	return 0;
152}
153
154static const struct dw_mci_drv_data starfive_data = {
155	.common_caps		= MMC_CAP_CMD23,
156	.set_ios		= dw_mci_starfive_set_ios,
157	.parse_dt		= dw_mci_starfive_parse_dt,
158	.execute_tuning		= dw_mci_starfive_execute_tuning,
159};
160
161static const struct of_device_id dw_mci_starfive_match[] = {
162	{ .compatible = "starfive,jh7110-mmc",
163		.data = &starfive_data },
164	{},
165};
166MODULE_DEVICE_TABLE(of, dw_mci_starfive_match);
167
168static int dw_mci_starfive_probe(struct platform_device *pdev)
169{
170	return dw_mci_pltfm_register(pdev, &starfive_data);
171}
172
173static struct platform_driver dw_mci_starfive_driver = {
174	.probe = dw_mci_starfive_probe,
175	.remove_new = dw_mci_pltfm_remove,
176	.driver = {
177		.name = "dwmmc_starfive",
178		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
179		.of_match_table = dw_mci_starfive_match,
180	},
181};
182module_platform_driver(dw_mci_starfive_driver);
183
184MODULE_DESCRIPTION("StarFive JH7110 Specific DW-MSHC Driver Extension");
185MODULE_LICENSE("GPL");
186MODULE_ALIAS("platform:dwmmc_starfive");
187