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1/*
2 * CBUS I2C driver for Nokia Internet Tablets.
3 *
4 * Copyright (C) 2004-2010 Nokia Corporation
5 *
6 * Based on code written by Juha Yrjölä, David Weinehall, Mikko Ylinen and
7 * Felipe Balbi. Converted to I2C driver by Aaro Koskinen.
8 *
9 * This file is subject to the terms and conditions of the GNU General
10 * Public License. See the file "COPYING" in the main directory of this
11 * archive for more details.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 */
18
19#include <linux/io.h>
20#include <linux/i2c.h>
21#include <linux/slab.h>
22#include <linux/delay.h>
23#include <linux/errno.h>
24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/gpio/consumer.h>
27#include <linux/interrupt.h>
28#include <linux/platform_device.h>
29
30/*
31 * Bit counts are derived from Nokia implementation. These should be checked
32 * if other CBUS implementations appear.
33 */
34#define CBUS_ADDR_BITS 3
35#define CBUS_REG_BITS 5
36
37struct cbus_host {
38 spinlock_t lock; /* host lock */
39 struct device *dev;
40 struct gpio_desc *clk;
41 struct gpio_desc *dat;
42 struct gpio_desc *sel;
43};
44
45/**
46 * cbus_send_bit - sends one bit over the bus
47 * @host: the host we're using
48 * @bit: one bit of information to send
49 */
50static void cbus_send_bit(struct cbus_host *host, unsigned bit)
51{
52 gpiod_set_value(host->dat, bit ? 1 : 0);
53 gpiod_set_value(host->clk, 1);
54 gpiod_set_value(host->clk, 0);
55}
56
57/**
58 * cbus_send_data - sends @len amount of data over the bus
59 * @host: the host we're using
60 * @data: the data to send
61 * @len: size of the transfer
62 */
63static void cbus_send_data(struct cbus_host *host, unsigned data, unsigned len)
64{
65 int i;
66
67 for (i = len; i > 0; i--)
68 cbus_send_bit(host, data & (1 << (i - 1)));
69}
70
71/**
72 * cbus_receive_bit - receives one bit from the bus
73 * @host: the host we're using
74 */
75static int cbus_receive_bit(struct cbus_host *host)
76{
77 int ret;
78
79 gpiod_set_value(host->clk, 1);
80 ret = gpiod_get_value(host->dat);
81 gpiod_set_value(host->clk, 0);
82 return ret;
83}
84
85/**
86 * cbus_receive_word - receives 16-bit word from the bus
87 * @host: the host we're using
88 */
89static int cbus_receive_word(struct cbus_host *host)
90{
91 int ret = 0;
92 int i;
93
94 for (i = 16; i > 0; i--) {
95 int bit = cbus_receive_bit(host);
96
97 if (bit < 0)
98 return bit;
99
100 if (bit)
101 ret |= 1 << (i - 1);
102 }
103 return ret;
104}
105
106/**
107 * cbus_transfer - transfers data over the bus
108 * @host: the host we're using
109 * @rw: read/write flag
110 * @dev: device address
111 * @reg: register address
112 * @data: if @rw == I2C_SBUS_WRITE data to send otherwise 0
113 */
114static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev,
115 unsigned reg, unsigned data)
116{
117 unsigned long flags;
118 int ret;
119
120 /* We don't want interrupts disturbing our transfer */
121 spin_lock_irqsave(&host->lock, flags);
122
123 /* Reset state and start of transfer, SEL stays down during transfer */
124 gpiod_set_value(host->sel, 0);
125
126 /* Set the DAT pin to output */
127 gpiod_direction_output(host->dat, 1);
128
129 /* Send the device address */
130 cbus_send_data(host, dev, CBUS_ADDR_BITS);
131
132 /* Send the rw flag */
133 cbus_send_bit(host, rw == I2C_SMBUS_READ);
134
135 /* Send the register address */
136 cbus_send_data(host, reg, CBUS_REG_BITS);
137
138 if (rw == I2C_SMBUS_WRITE) {
139 cbus_send_data(host, data, 16);
140 ret = 0;
141 } else {
142 ret = gpiod_direction_input(host->dat);
143 if (ret) {
144 dev_dbg(host->dev, "failed setting direction\n");
145 goto out;
146 }
147 gpiod_set_value(host->clk, 1);
148
149 ret = cbus_receive_word(host);
150 if (ret < 0) {
151 dev_dbg(host->dev, "failed receiving data\n");
152 goto out;
153 }
154 }
155
156 /* Indicate end of transfer, SEL goes up until next transfer */
157 gpiod_set_value(host->sel, 1);
158 gpiod_set_value(host->clk, 1);
159 gpiod_set_value(host->clk, 0);
160
161out:
162 spin_unlock_irqrestore(&host->lock, flags);
163
164 return ret;
165}
166
167static int cbus_i2c_smbus_xfer(struct i2c_adapter *adapter,
168 u16 addr,
169 unsigned short flags,
170 char read_write,
171 u8 command,
172 int size,
173 union i2c_smbus_data *data)
174{
175 struct cbus_host *chost = i2c_get_adapdata(adapter);
176 int ret;
177
178 if (size != I2C_SMBUS_WORD_DATA)
179 return -EINVAL;
180
181 ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr,
182 command, data->word);
183 if (ret < 0)
184 return ret;
185
186 if (read_write == I2C_SMBUS_READ)
187 data->word = ret;
188
189 return 0;
190}
191
192static u32 cbus_i2c_func(struct i2c_adapter *adapter)
193{
194 return I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA;
195}
196
197static const struct i2c_algorithm cbus_i2c_algo = {
198 .smbus_xfer = cbus_i2c_smbus_xfer,
199 .smbus_xfer_atomic = cbus_i2c_smbus_xfer,
200 .functionality = cbus_i2c_func,
201};
202
203static void cbus_i2c_remove(struct platform_device *pdev)
204{
205 struct i2c_adapter *adapter = platform_get_drvdata(pdev);
206
207 i2c_del_adapter(adapter);
208}
209
210static int cbus_i2c_probe(struct platform_device *pdev)
211{
212 struct i2c_adapter *adapter;
213 struct cbus_host *chost;
214
215 adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter),
216 GFP_KERNEL);
217 if (!adapter)
218 return -ENOMEM;
219
220 chost = devm_kzalloc(&pdev->dev, sizeof(*chost), GFP_KERNEL);
221 if (!chost)
222 return -ENOMEM;
223
224 if (gpiod_count(&pdev->dev, NULL) != 3)
225 return -ENODEV;
226 chost->clk = devm_gpiod_get_index(&pdev->dev, NULL, 0, GPIOD_OUT_LOW);
227 if (IS_ERR(chost->clk))
228 return PTR_ERR(chost->clk);
229 chost->dat = devm_gpiod_get_index(&pdev->dev, NULL, 1, GPIOD_IN);
230 if (IS_ERR(chost->dat))
231 return PTR_ERR(chost->dat);
232 chost->sel = devm_gpiod_get_index(&pdev->dev, NULL, 2, GPIOD_OUT_HIGH);
233 if (IS_ERR(chost->sel))
234 return PTR_ERR(chost->sel);
235 gpiod_set_consumer_name(chost->clk, "CBUS clk");
236 gpiod_set_consumer_name(chost->dat, "CBUS dat");
237 gpiod_set_consumer_name(chost->sel, "CBUS sel");
238
239 adapter->owner = THIS_MODULE;
240 adapter->class = I2C_CLASS_HWMON;
241 adapter->dev.parent = &pdev->dev;
242 adapter->dev.of_node = pdev->dev.of_node;
243 adapter->nr = pdev->id;
244 adapter->timeout = HZ;
245 adapter->algo = &cbus_i2c_algo;
246 strscpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name));
247
248 spin_lock_init(&chost->lock);
249 chost->dev = &pdev->dev;
250
251 i2c_set_adapdata(adapter, chost);
252 platform_set_drvdata(pdev, adapter);
253
254 return i2c_add_numbered_adapter(adapter);
255}
256
257#if defined(CONFIG_OF)
258static const struct of_device_id i2c_cbus_dt_ids[] = {
259 { .compatible = "i2c-cbus-gpio", },
260 { }
261};
262MODULE_DEVICE_TABLE(of, i2c_cbus_dt_ids);
263#endif
264
265static struct platform_driver cbus_i2c_driver = {
266 .probe = cbus_i2c_probe,
267 .remove_new = cbus_i2c_remove,
268 .driver = {
269 .name = "i2c-cbus-gpio",
270 .of_match_table = of_match_ptr(i2c_cbus_dt_ids),
271 },
272};
273module_platform_driver(cbus_i2c_driver);
274
275MODULE_ALIAS("platform:i2c-cbus-gpio");
276MODULE_DESCRIPTION("CBUS I2C driver");
277MODULE_AUTHOR("Juha Yrjölä");
278MODULE_AUTHOR("David Weinehall");
279MODULE_AUTHOR("Mikko Ylinen");
280MODULE_AUTHOR("Felipe Balbi");
281MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
282MODULE_LICENSE("GPL");
1/*
2 * CBUS I2C driver for Nokia Internet Tablets.
3 *
4 * Copyright (C) 2004-2010 Nokia Corporation
5 *
6 * Based on code written by Juha Yrjölä, David Weinehall, Mikko Ylinen and
7 * Felipe Balbi. Converted to I2C driver by Aaro Koskinen.
8 *
9 * This file is subject to the terms and conditions of the GNU General
10 * Public License. See the file "COPYING" in the main directory of this
11 * archive for more details.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 */
18
19#include <linux/io.h>
20#include <linux/i2c.h>
21#include <linux/slab.h>
22#include <linux/delay.h>
23#include <linux/errno.h>
24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/gpio/consumer.h>
27#include <linux/interrupt.h>
28#include <linux/platform_device.h>
29
30/*
31 * Bit counts are derived from Nokia implementation. These should be checked
32 * if other CBUS implementations appear.
33 */
34#define CBUS_ADDR_BITS 3
35#define CBUS_REG_BITS 5
36
37struct cbus_host {
38 spinlock_t lock; /* host lock */
39 struct device *dev;
40 struct gpio_desc *clk;
41 struct gpio_desc *dat;
42 struct gpio_desc *sel;
43};
44
45/**
46 * cbus_send_bit - sends one bit over the bus
47 * @host: the host we're using
48 * @bit: one bit of information to send
49 */
50static void cbus_send_bit(struct cbus_host *host, unsigned bit)
51{
52 gpiod_set_value(host->dat, bit ? 1 : 0);
53 gpiod_set_value(host->clk, 1);
54 gpiod_set_value(host->clk, 0);
55}
56
57/**
58 * cbus_send_data - sends @len amount of data over the bus
59 * @host: the host we're using
60 * @data: the data to send
61 * @len: size of the transfer
62 */
63static void cbus_send_data(struct cbus_host *host, unsigned data, unsigned len)
64{
65 int i;
66
67 for (i = len; i > 0; i--)
68 cbus_send_bit(host, data & (1 << (i - 1)));
69}
70
71/**
72 * cbus_receive_bit - receives one bit from the bus
73 * @host: the host we're using
74 */
75static int cbus_receive_bit(struct cbus_host *host)
76{
77 int ret;
78
79 gpiod_set_value(host->clk, 1);
80 ret = gpiod_get_value(host->dat);
81 gpiod_set_value(host->clk, 0);
82 return ret;
83}
84
85/**
86 * cbus_receive_word - receives 16-bit word from the bus
87 * @host: the host we're using
88 */
89static int cbus_receive_word(struct cbus_host *host)
90{
91 int ret = 0;
92 int i;
93
94 for (i = 16; i > 0; i--) {
95 int bit = cbus_receive_bit(host);
96
97 if (bit < 0)
98 return bit;
99
100 if (bit)
101 ret |= 1 << (i - 1);
102 }
103 return ret;
104}
105
106/**
107 * cbus_transfer - transfers data over the bus
108 * @host: the host we're using
109 * @rw: read/write flag
110 * @dev: device address
111 * @reg: register address
112 * @data: if @rw == I2C_SBUS_WRITE data to send otherwise 0
113 */
114static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev,
115 unsigned reg, unsigned data)
116{
117 unsigned long flags;
118 int ret;
119
120 /* We don't want interrupts disturbing our transfer */
121 spin_lock_irqsave(&host->lock, flags);
122
123 /* Reset state and start of transfer, SEL stays down during transfer */
124 gpiod_set_value(host->sel, 0);
125
126 /* Set the DAT pin to output */
127 gpiod_direction_output(host->dat, 1);
128
129 /* Send the device address */
130 cbus_send_data(host, dev, CBUS_ADDR_BITS);
131
132 /* Send the rw flag */
133 cbus_send_bit(host, rw == I2C_SMBUS_READ);
134
135 /* Send the register address */
136 cbus_send_data(host, reg, CBUS_REG_BITS);
137
138 if (rw == I2C_SMBUS_WRITE) {
139 cbus_send_data(host, data, 16);
140 ret = 0;
141 } else {
142 ret = gpiod_direction_input(host->dat);
143 if (ret) {
144 dev_dbg(host->dev, "failed setting direction\n");
145 goto out;
146 }
147 gpiod_set_value(host->clk, 1);
148
149 ret = cbus_receive_word(host);
150 if (ret < 0) {
151 dev_dbg(host->dev, "failed receiving data\n");
152 goto out;
153 }
154 }
155
156 /* Indicate end of transfer, SEL goes up until next transfer */
157 gpiod_set_value(host->sel, 1);
158 gpiod_set_value(host->clk, 1);
159 gpiod_set_value(host->clk, 0);
160
161out:
162 spin_unlock_irqrestore(&host->lock, flags);
163
164 return ret;
165}
166
167static int cbus_i2c_smbus_xfer(struct i2c_adapter *adapter,
168 u16 addr,
169 unsigned short flags,
170 char read_write,
171 u8 command,
172 int size,
173 union i2c_smbus_data *data)
174{
175 struct cbus_host *chost = i2c_get_adapdata(adapter);
176 int ret;
177
178 if (size != I2C_SMBUS_WORD_DATA)
179 return -EINVAL;
180
181 ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr,
182 command, data->word);
183 if (ret < 0)
184 return ret;
185
186 if (read_write == I2C_SMBUS_READ)
187 data->word = ret;
188
189 return 0;
190}
191
192static u32 cbus_i2c_func(struct i2c_adapter *adapter)
193{
194 return I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA;
195}
196
197static const struct i2c_algorithm cbus_i2c_algo = {
198 .smbus_xfer = cbus_i2c_smbus_xfer,
199 .smbus_xfer_atomic = cbus_i2c_smbus_xfer,
200 .functionality = cbus_i2c_func,
201};
202
203static void cbus_i2c_remove(struct platform_device *pdev)
204{
205 struct i2c_adapter *adapter = platform_get_drvdata(pdev);
206
207 i2c_del_adapter(adapter);
208}
209
210static int cbus_i2c_probe(struct platform_device *pdev)
211{
212 struct i2c_adapter *adapter;
213 struct cbus_host *chost;
214
215 adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter),
216 GFP_KERNEL);
217 if (!adapter)
218 return -ENOMEM;
219
220 chost = devm_kzalloc(&pdev->dev, sizeof(*chost), GFP_KERNEL);
221 if (!chost)
222 return -ENOMEM;
223
224 if (gpiod_count(&pdev->dev, NULL) != 3)
225 return -ENODEV;
226 chost->clk = devm_gpiod_get_index(&pdev->dev, NULL, 0, GPIOD_OUT_LOW);
227 if (IS_ERR(chost->clk))
228 return PTR_ERR(chost->clk);
229 chost->dat = devm_gpiod_get_index(&pdev->dev, NULL, 1, GPIOD_IN);
230 if (IS_ERR(chost->dat))
231 return PTR_ERR(chost->dat);
232 chost->sel = devm_gpiod_get_index(&pdev->dev, NULL, 2, GPIOD_OUT_HIGH);
233 if (IS_ERR(chost->sel))
234 return PTR_ERR(chost->sel);
235 gpiod_set_consumer_name(chost->clk, "CBUS clk");
236 gpiod_set_consumer_name(chost->dat, "CBUS dat");
237 gpiod_set_consumer_name(chost->sel, "CBUS sel");
238
239 adapter->owner = THIS_MODULE;
240 adapter->class = I2C_CLASS_HWMON;
241 adapter->dev.parent = &pdev->dev;
242 adapter->dev.of_node = pdev->dev.of_node;
243 adapter->nr = pdev->id;
244 adapter->timeout = HZ;
245 adapter->algo = &cbus_i2c_algo;
246 strscpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name));
247
248 spin_lock_init(&chost->lock);
249 chost->dev = &pdev->dev;
250
251 i2c_set_adapdata(adapter, chost);
252 platform_set_drvdata(pdev, adapter);
253
254 return i2c_add_numbered_adapter(adapter);
255}
256
257#if defined(CONFIG_OF)
258static const struct of_device_id i2c_cbus_dt_ids[] = {
259 { .compatible = "i2c-cbus-gpio", },
260 { }
261};
262MODULE_DEVICE_TABLE(of, i2c_cbus_dt_ids);
263#endif
264
265static struct platform_driver cbus_i2c_driver = {
266 .probe = cbus_i2c_probe,
267 .remove_new = cbus_i2c_remove,
268 .driver = {
269 .name = "i2c-cbus-gpio",
270 .of_match_table = of_match_ptr(i2c_cbus_dt_ids),
271 },
272};
273module_platform_driver(cbus_i2c_driver);
274
275MODULE_ALIAS("platform:i2c-cbus-gpio");
276MODULE_DESCRIPTION("CBUS I2C driver");
277MODULE_AUTHOR("Juha Yrjölä");
278MODULE_AUTHOR("David Weinehall");
279MODULE_AUTHOR("Mikko Ylinen");
280MODULE_AUTHOR("Felipe Balbi");
281MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
282MODULE_LICENSE("GPL");