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 return dev_err_probe(i2c->dev, err, "failed to enable clock\n");
49
50 err = clk_set_rate(i2c->clk, 20000000);
51 if (err) {
52 clk_disable_unprepare(i2c->clk);
53 return dev_err_probe(i2c->dev, err, "failed to set clock = 20Mhz\n");
54 }
55
56 writew(0, i2c->base + VIAI2C_REG_CR);
57 writew(MCR_APB_166M, i2c->base + VIAI2C_REG_MCR);
58 writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);
59 writew(VIAI2C_IMR_ENABLE_ALL, i2c->base + VIAI2C_REG_IMR);
60 writew(VIAI2C_CR_ENABLE, i2c->base + VIAI2C_REG_CR);
61 readw(i2c->base + VIAI2C_REG_CSR); /* read clear */
62 writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);
63
64 if (i2c->tcr == VIAI2C_TCR_FAST)
65 writew(SCL_TIMEOUT(128) | TR_HS, i2c->base + VIAI2C_REG_TR);
66 else
67 writew(SCL_TIMEOUT(128) | TR_STD, i2c->base + VIAI2C_REG_TR);
68
69 return 0;
70 }
71
wmt_i2c_isr(int irq,void * data)72 static irqreturn_t wmt_i2c_isr(int irq, void *data)
73 {
74 struct viai2c *i2c = data;
75 u8 status;
76
77 /* save the status and write-clear it */
78 status = readw(i2c->base + VIAI2C_REG_ISR);
79 writew(status, i2c->base + VIAI2C_REG_ISR);
80
81 i2c->ret = 0;
82 if (status & VIAI2C_ISR_NACK_ADDR)
83 i2c->ret = -EIO;
84
85 if (status & VIAI2C_ISR_SCL_TIMEOUT)
86 i2c->ret = -ETIMEDOUT;
87
88 if (!i2c->ret)
89 i2c->ret = viai2c_irq_xfer(i2c);
90
91 /* All the data has been successfully transferred or error occurred */
92 if (i2c->ret)
93 complete(&i2c->complete);
94
95 return IRQ_HANDLED;
96 }
97
wmt_i2c_probe(struct platform_device * pdev)98 static int wmt_i2c_probe(struct platform_device *pdev)
99 {
100 struct device_node *np = pdev->dev.of_node;
101 struct viai2c *i2c;
102 struct i2c_adapter *adap;
103 int err;
104 u32 clk_rate;
105
106 err = viai2c_init(pdev, &i2c, VIAI2C_PLAT_WMT);
107 if (err)
108 return err;
109
110 i2c->irq = platform_get_irq(pdev, 0);
111 if (i2c->irq < 0)
112 return i2c->irq;
113
114 err = devm_request_irq(&pdev->dev, i2c->irq, wmt_i2c_isr,
115 0, pdev->name, i2c);
116 if (err)
117 return dev_err_probe(&pdev->dev, err,
118 "failed to request irq %i\n", i2c->irq);
119
120 i2c->clk = of_clk_get(np, 0);
121 if (IS_ERR(i2c->clk))
122 return dev_err_probe(&pdev->dev, PTR_ERR(i2c->clk),
123 "unable to request clock\n");
124
125 err = of_property_read_u32(np, "clock-frequency", &clk_rate);
126 if (!err && clk_rate == I2C_MAX_FAST_MODE_FREQ)
127 i2c->tcr = VIAI2C_TCR_FAST;
128
129 adap = &i2c->adapter;
130 i2c_set_adapdata(adap, i2c);
131 strscpy(adap->name, "WMT I2C adapter", sizeof(adap->name));
132 adap->owner = THIS_MODULE;
133 adap->algo = &wmt_i2c_algo;
134 adap->dev.parent = &pdev->dev;
135 adap->dev.of_node = pdev->dev.of_node;
136
137 err = wmt_i2c_reset_hardware(i2c);
138 if (err)
139 return err;
140
141 err = i2c_add_adapter(adap);
142 if (err)
143 /* wmt_i2c_reset_hardware() enables i2c_dev->clk */
144 clk_disable_unprepare(i2c->clk);
145
146 return err;
147 }
148
wmt_i2c_remove(struct platform_device * pdev)149 static void wmt_i2c_remove(struct platform_device *pdev)
150 {
151 struct viai2c *i2c = platform_get_drvdata(pdev);
152
153 /* Disable interrupts, clock and delete adapter */
154 writew(0, i2c->base + VIAI2C_REG_IMR);
155 clk_disable_unprepare(i2c->clk);
156 i2c_del_adapter(&i2c->adapter);
157 }
158
159 static const struct of_device_id wmt_i2c_dt_ids[] = {
160 { .compatible = "wm,wm8505-i2c" },
161 { /* Sentinel */ },
162 };
163
164 static struct platform_driver wmt_i2c_driver = {
165 .probe = wmt_i2c_probe,
166 .remove = wmt_i2c_remove,
167 .driver = {
168 .name = "wmt-i2c",
169 .of_match_table = wmt_i2c_dt_ids,
170 },
171 };
172
173 module_platform_driver(wmt_i2c_driver);
174
175 MODULE_DESCRIPTION("Wondermedia I2C controller driver");
176 MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
177 MODULE_LICENSE("GPL");
178 MODULE_DEVICE_TABLE(of, wmt_i2c_dt_ids);
179