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 
23 struct 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 
31 static 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 
47 static 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 
90 tuning_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 
123 static 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 
154 static 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 
161 static const struct of_device_id dw_mci_starfive_match[] = {
162 	{ .compatible = "starfive,jh7110-mmc",
163 		.data = &starfive_data },
164 	{},
165 };
166 MODULE_DEVICE_TABLE(of, dw_mci_starfive_match);
167 
168 static int dw_mci_starfive_probe(struct platform_device *pdev)
169 {
170 	return dw_mci_pltfm_register(pdev, &starfive_data);
171 }
172 
173 static 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 };
182 module_platform_driver(dw_mci_starfive_driver);
183 
184 MODULE_DESCRIPTION("StarFive JH7110 Specific DW-MSHC Driver Extension");
185 MODULE_LICENSE("GPL");
186 MODULE_ALIAS("platform:dwmmc_starfive");
187