1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * IMG Pistachio USB PHY driver
4  *
5  * Copyright (C) 2015 Google, Inc.
6  */
7 
8 #include <linux/clk.h>
9 #include <linux/delay.h>
10 #include <linux/io.h>
11 #include <linux/kernel.h>
12 #include <linux/mfd/syscon.h>
13 #include <linux/module.h>
14 #include <linux/of.h>
15 #include <linux/phy/phy.h>
16 #include <linux/platform_device.h>
17 #include <linux/regmap.h>
18 
19 #include <dt-bindings/phy/phy-pistachio-usb.h>
20 
21 #define USB_PHY_CONTROL1				0x04
22 #define USB_PHY_CONTROL1_FSEL_SHIFT			2
23 #define USB_PHY_CONTROL1_FSEL_MASK			0x7
24 
25 #define USB_PHY_STRAP_CONTROL				0x10
26 #define USB_PHY_STRAP_CONTROL_REFCLK_SHIFT		4
27 #define USB_PHY_STRAP_CONTROL_REFCLK_MASK		0x3
28 
29 #define USB_PHY_STATUS					0x14
30 #define USB_PHY_STATUS_RX_PHY_CLK			BIT(9)
31 #define USB_PHY_STATUS_RX_UTMI_CLK			BIT(8)
32 #define USB_PHY_STATUS_VBUS_FAULT			BIT(7)
33 
34 struct pistachio_usb_phy {
35 	struct device *dev;
36 	struct regmap *cr_top;
37 	struct clk *phy_clk;
38 	unsigned int refclk;
39 };
40 
41 static const unsigned long fsel_rate_map[] = {
42 	9600000,
43 	10000000,
44 	12000000,
45 	19200000,
46 	20000000,
47 	24000000,
48 	0,
49 	50000000,
50 };
51 
pistachio_usb_phy_power_on(struct phy * phy)52 static int pistachio_usb_phy_power_on(struct phy *phy)
53 {
54 	struct pistachio_usb_phy *p_phy = phy_get_drvdata(phy);
55 	unsigned long timeout, rate;
56 	unsigned int i;
57 	int ret;
58 
59 	ret = clk_prepare_enable(p_phy->phy_clk);
60 	if (ret < 0) {
61 		dev_err(p_phy->dev, "Failed to enable PHY clock: %d\n", ret);
62 		return ret;
63 	}
64 
65 	regmap_update_bits(p_phy->cr_top, USB_PHY_STRAP_CONTROL,
66 			   USB_PHY_STRAP_CONTROL_REFCLK_MASK <<
67 			   USB_PHY_STRAP_CONTROL_REFCLK_SHIFT,
68 			   p_phy->refclk << USB_PHY_STRAP_CONTROL_REFCLK_SHIFT);
69 
70 	rate = clk_get_rate(p_phy->phy_clk);
71 	if (p_phy->refclk == REFCLK_XO_CRYSTAL && rate != 12000000) {
72 		dev_err(p_phy->dev, "Unsupported rate for XO crystal: %ld\n",
73 			rate);
74 		ret = -EINVAL;
75 		goto disable_clk;
76 	}
77 
78 	for (i = 0; i < ARRAY_SIZE(fsel_rate_map); i++) {
79 		if (rate == fsel_rate_map[i])
80 			break;
81 	}
82 	if (i == ARRAY_SIZE(fsel_rate_map)) {
83 		dev_err(p_phy->dev, "Unsupported clock rate: %lu\n", rate);
84 		ret = -EINVAL;
85 		goto disable_clk;
86 	}
87 
88 	regmap_update_bits(p_phy->cr_top, USB_PHY_CONTROL1,
89 			   USB_PHY_CONTROL1_FSEL_MASK <<
90 			   USB_PHY_CONTROL1_FSEL_SHIFT,
91 			   i << USB_PHY_CONTROL1_FSEL_SHIFT);
92 
93 	timeout = jiffies + msecs_to_jiffies(200);
94 	while (time_before(jiffies, timeout)) {
95 		unsigned int val;
96 
97 		regmap_read(p_phy->cr_top, USB_PHY_STATUS, &val);
98 		if (val & USB_PHY_STATUS_VBUS_FAULT) {
99 			dev_err(p_phy->dev, "VBUS fault detected\n");
100 			ret = -EIO;
101 			goto disable_clk;
102 		}
103 		if ((val & USB_PHY_STATUS_RX_PHY_CLK) &&
104 		    (val & USB_PHY_STATUS_RX_UTMI_CLK))
105 			return 0;
106 		usleep_range(1000, 1500);
107 	}
108 
109 	dev_err(p_phy->dev, "Timed out waiting for PHY to power on\n");
110 	ret = -ETIMEDOUT;
111 
112 disable_clk:
113 	clk_disable_unprepare(p_phy->phy_clk);
114 	return ret;
115 }
116 
pistachio_usb_phy_power_off(struct phy * phy)117 static int pistachio_usb_phy_power_off(struct phy *phy)
118 {
119 	struct pistachio_usb_phy *p_phy = phy_get_drvdata(phy);
120 
121 	clk_disable_unprepare(p_phy->phy_clk);
122 
123 	return 0;
124 }
125 
126 static const struct phy_ops pistachio_usb_phy_ops = {
127 	.power_on = pistachio_usb_phy_power_on,
128 	.power_off = pistachio_usb_phy_power_off,
129 	.owner = THIS_MODULE,
130 };
131 
pistachio_usb_phy_probe(struct platform_device * pdev)132 static int pistachio_usb_phy_probe(struct platform_device *pdev)
133 {
134 	struct pistachio_usb_phy *p_phy;
135 	struct phy_provider *provider;
136 	struct phy *phy;
137 	int ret;
138 
139 	p_phy = devm_kzalloc(&pdev->dev, sizeof(*p_phy), GFP_KERNEL);
140 	if (!p_phy)
141 		return -ENOMEM;
142 	p_phy->dev = &pdev->dev;
143 	platform_set_drvdata(pdev, p_phy);
144 
145 	p_phy->cr_top = syscon_regmap_lookup_by_phandle(p_phy->dev->of_node,
146 							"img,cr-top");
147 	if (IS_ERR(p_phy->cr_top)) {
148 		dev_err(p_phy->dev, "Failed to get CR_TOP registers: %ld\n",
149 			PTR_ERR(p_phy->cr_top));
150 		return PTR_ERR(p_phy->cr_top);
151 	}
152 
153 	p_phy->phy_clk = devm_clk_get(p_phy->dev, "usb_phy");
154 	if (IS_ERR(p_phy->phy_clk)) {
155 		dev_err(p_phy->dev, "Failed to get usb_phy clock: %ld\n",
156 			PTR_ERR(p_phy->phy_clk));
157 		return PTR_ERR(p_phy->phy_clk);
158 	}
159 
160 	ret = of_property_read_u32(p_phy->dev->of_node, "img,refclk",
161 				   &p_phy->refclk);
162 	if (ret < 0) {
163 		dev_err(p_phy->dev, "No reference clock selector specified\n");
164 		return ret;
165 	}
166 
167 	phy = devm_phy_create(p_phy->dev, NULL, &pistachio_usb_phy_ops);
168 	if (IS_ERR(phy)) {
169 		dev_err(p_phy->dev, "Failed to create PHY: %ld\n",
170 			PTR_ERR(phy));
171 		return PTR_ERR(phy);
172 	}
173 	phy_set_drvdata(phy, p_phy);
174 
175 	provider = devm_of_phy_provider_register(p_phy->dev,
176 						 of_phy_simple_xlate);
177 	if (IS_ERR(provider)) {
178 		dev_err(p_phy->dev, "Failed to register PHY provider: %ld\n",
179 			PTR_ERR(provider));
180 		return PTR_ERR(provider);
181 	}
182 
183 	return 0;
184 }
185 
186 static const struct of_device_id pistachio_usb_phy_of_match[] = {
187 	{ .compatible = "img,pistachio-usb-phy", },
188 	{ },
189 };
190 MODULE_DEVICE_TABLE(of, pistachio_usb_phy_of_match);
191 
192 static struct platform_driver pistachio_usb_phy_driver = {
193 	.probe		= pistachio_usb_phy_probe,
194 	.driver		= {
195 		.name	= "pistachio-usb-phy",
196 		.of_match_table = pistachio_usb_phy_of_match,
197 	},
198 };
199 module_platform_driver(pistachio_usb_phy_driver);
200 
201 MODULE_AUTHOR("Andrew Bresticker <abrestic@chromium.org>");
202 MODULE_DESCRIPTION("IMG Pistachio USB2.0 PHY driver");
203 MODULE_LICENSE("GPL v2");
204