1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Wondermedia I2C Controller Driver
4 *
5 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
6 *
7 * Derived from GPLv2+ licensed source:
8 * - Copyright (C) 2008 WonderMedia Technologies, Inc.
9 */
10
11 #include <linux/clk.h>
12 #include <linux/of.h>
13 #include <linux/of_address.h>
14 #include "i2c-viai2c-common.h"
15
16 #define REG_SLAVE_CR 0x10
17 #define REG_SLAVE_SR 0x12
18 #define REG_SLAVE_ISR 0x14
19 #define REG_SLAVE_IMR 0x16
20 #define REG_SLAVE_DR 0x18
21 #define REG_SLAVE_TR 0x1A
22
23 /* REG_TR */
24 #define SCL_TIMEOUT(x) (((x) & 0xFF) << 8)
25 #define TR_STD 0x0064
26 #define TR_HS 0x0019
27
28 /* REG_MCR */
29 #define MCR_APB_96M 7
30 #define MCR_APB_166M 12
31
wmt_i2c_func(struct i2c_adapter * adap)32 static u32 wmt_i2c_func(struct i2c_adapter *adap)
33 {
34 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
35 }
36
37 static const struct i2c_algorithm wmt_i2c_algo = {
38 .xfer = viai2c_xfer,
39 .functionality = wmt_i2c_func,
40 };
41
wmt_i2c_reset_hardware(struct viai2c * i2c)42 static int wmt_i2c_reset_hardware(struct viai2c *i2c)
43 {
44 int err;
45
46 err = clk_prepare_enable(i2c->clk);
47 if (err) {
48 dev_err(i2c->dev, "failed to enable clock\n");
49 return err;
50 }
51
52 err = clk_set_rate(i2c->clk, 20000000);
53 if (err) {
54 dev_err(i2c->dev, "failed to set clock = 20Mhz\n");
55 clk_disable_unprepare(i2c->clk);
56 return err;
57 }
58
59 writew(0, i2c->base + VIAI2C_REG_CR);
60 writew(MCR_APB_166M, i2c->base + VIAI2C_REG_MCR);
61 writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);
62 writew(VIAI2C_IMR_ENABLE_ALL, i2c->base + VIAI2C_REG_IMR);
63 writew(VIAI2C_CR_ENABLE, i2c->base + VIAI2C_REG_CR);
64 readw(i2c->base + VIAI2C_REG_CSR); /* read clear */
65 writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);
66
67 if (i2c->tcr == VIAI2C_TCR_FAST)
68 writew(SCL_TIMEOUT(128) | TR_HS, i2c->base + VIAI2C_REG_TR);
69 else
70 writew(SCL_TIMEOUT(128) | TR_STD, i2c->base + VIAI2C_REG_TR);
71
72 return 0;
73 }
74
wmt_i2c_isr(int irq,void * data)75 static irqreturn_t wmt_i2c_isr(int irq, void *data)
76 {
77 struct viai2c *i2c = data;
78 u8 status;
79
80 /* save the status and write-clear it */
81 status = readw(i2c->base + VIAI2C_REG_ISR);
82 writew(status, i2c->base + VIAI2C_REG_ISR);
83
84 i2c->ret = 0;
85 if (status & VIAI2C_ISR_NACK_ADDR)
86 i2c->ret = -EIO;
87
88 if (status & VIAI2C_ISR_SCL_TIMEOUT)
89 i2c->ret = -ETIMEDOUT;
90
91 if (!i2c->ret)
92 i2c->ret = viai2c_irq_xfer(i2c);
93
94 /* All the data has been successfully transferred or error occurred */
95 if (i2c->ret)
96 complete(&i2c->complete);
97
98 return IRQ_HANDLED;
99 }
100
wmt_i2c_probe(struct platform_device * pdev)101 static int wmt_i2c_probe(struct platform_device *pdev)
102 {
103 struct device_node *np = pdev->dev.of_node;
104 struct viai2c *i2c;
105 struct i2c_adapter *adap;
106 int err;
107 u32 clk_rate;
108
109 err = viai2c_init(pdev, &i2c, VIAI2C_PLAT_WMT);
110 if (err)
111 return err;
112
113 i2c->irq = platform_get_irq(pdev, 0);
114 if (i2c->irq < 0)
115 return i2c->irq;
116
117 err = devm_request_irq(&pdev->dev, i2c->irq, wmt_i2c_isr,
118 0, pdev->name, i2c);
119 if (err)
120 return dev_err_probe(&pdev->dev, err,
121 "failed to request irq %i\n", i2c->irq);
122
123 i2c->clk = of_clk_get(np, 0);
124 if (IS_ERR(i2c->clk)) {
125 dev_err(&pdev->dev, "unable to request clock\n");
126 return PTR_ERR(i2c->clk);
127 }
128
129 err = of_property_read_u32(np, "clock-frequency", &clk_rate);
130 if (!err && clk_rate == I2C_MAX_FAST_MODE_FREQ)
131 i2c->tcr = VIAI2C_TCR_FAST;
132
133 adap = &i2c->adapter;
134 i2c_set_adapdata(adap, i2c);
135 strscpy(adap->name, "WMT I2C adapter", sizeof(adap->name));
136 adap->owner = THIS_MODULE;
137 adap->algo = &wmt_i2c_algo;
138 adap->dev.parent = &pdev->dev;
139 adap->dev.of_node = pdev->dev.of_node;
140
141 err = wmt_i2c_reset_hardware(i2c);
142 if (err) {
143 dev_err(&pdev->dev, "error initializing hardware\n");
144 return err;
145 }
146
147 err = i2c_add_adapter(adap);
148 if (err)
149 /* wmt_i2c_reset_hardware() enables i2c_dev->clk */
150 clk_disable_unprepare(i2c->clk);
151
152 return err;
153 }
154
wmt_i2c_remove(struct platform_device * pdev)155 static void wmt_i2c_remove(struct platform_device *pdev)
156 {
157 struct viai2c *i2c = platform_get_drvdata(pdev);
158
159 /* Disable interrupts, clock and delete adapter */
160 writew(0, i2c->base + VIAI2C_REG_IMR);
161 clk_disable_unprepare(i2c->clk);
162 i2c_del_adapter(&i2c->adapter);
163 }
164
165 static const struct of_device_id wmt_i2c_dt_ids[] = {
166 { .compatible = "wm,wm8505-i2c" },
167 { /* Sentinel */ },
168 };
169
170 static struct platform_driver wmt_i2c_driver = {
171 .probe = wmt_i2c_probe,
172 .remove_new = wmt_i2c_remove,
173 .driver = {
174 .name = "wmt-i2c",
175 .of_match_table = wmt_i2c_dt_ids,
176 },
177 };
178
179 module_platform_driver(wmt_i2c_driver);
180
181 MODULE_DESCRIPTION("Wondermedia I2C controller driver");
182 MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
183 MODULE_LICENSE("GPL");
184 MODULE_DEVICE_TABLE(of, wmt_i2c_dt_ids);
185