1/*
2 * Driver for the Diolan DLN-2 USB-I2C adapter
3 *
4 * Copyright (c) 2014 Intel Corporation
5 *
6 * Derived from:
7 *  i2c-diolan-u2c.c
8 *  Copyright (c) 2010-2011 Ericsson AB
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation, version 2.
13 */
14
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/types.h>
18#include <linux/slab.h>
19#include <linux/i2c.h>
20#include <linux/platform_device.h>
21#include <linux/mfd/dln2.h>
22
23#define DLN2_I2C_MODULE_ID		0x03
24#define DLN2_I2C_CMD(cmd)		DLN2_CMD(cmd, DLN2_I2C_MODULE_ID)
25
26/* I2C commands */
27#define DLN2_I2C_GET_PORT_COUNT		DLN2_I2C_CMD(0x00)
28#define DLN2_I2C_ENABLE			DLN2_I2C_CMD(0x01)
29#define DLN2_I2C_DISABLE		DLN2_I2C_CMD(0x02)
30#define DLN2_I2C_IS_ENABLED		DLN2_I2C_CMD(0x03)
31#define DLN2_I2C_WRITE			DLN2_I2C_CMD(0x06)
32#define DLN2_I2C_READ			DLN2_I2C_CMD(0x07)
33#define DLN2_I2C_SCAN_DEVICES		DLN2_I2C_CMD(0x08)
34#define DLN2_I2C_PULLUP_ENABLE		DLN2_I2C_CMD(0x09)
35#define DLN2_I2C_PULLUP_DISABLE		DLN2_I2C_CMD(0x0A)
36#define DLN2_I2C_PULLUP_IS_ENABLED	DLN2_I2C_CMD(0x0B)
37#define DLN2_I2C_TRANSFER		DLN2_I2C_CMD(0x0C)
38#define DLN2_I2C_SET_MAX_REPLY_COUNT	DLN2_I2C_CMD(0x0D)
39#define DLN2_I2C_GET_MAX_REPLY_COUNT	DLN2_I2C_CMD(0x0E)
40
41#define DLN2_I2C_MAX_XFER_SIZE		256
42#define DLN2_I2C_BUF_SIZE		(DLN2_I2C_MAX_XFER_SIZE + 16)
43
44struct dln2_i2c {
45	struct platform_device *pdev;
46	struct i2c_adapter adapter;
47	u8 port;
48	/*
49	 * Buffer to hold the packet for read or write transfers. One is enough
50	 * since we can't have multiple transfers in parallel on the i2c bus.
51	 */
52	void *buf;
53};
54
55static int dln2_i2c_enable(struct dln2_i2c *dln2, bool enable)
56{
57	u16 cmd;
58	struct {
59		u8 port;
60	} tx;
61
62	tx.port = dln2->port;
63
64	if (enable)
65		cmd = DLN2_I2C_ENABLE;
66	else
67		cmd = DLN2_I2C_DISABLE;
68
69	return dln2_transfer_tx(dln2->pdev, cmd, &tx, sizeof(tx));
70}
71
72static int dln2_i2c_write(struct dln2_i2c *dln2, u8 addr,
73			  u8 *data, u16 data_len)
74{
75	int ret;
76	struct {
77		u8 port;
78		u8 addr;
79		u8 mem_addr_len;
80		__le32 mem_addr;
81		__le16 buf_len;
82		u8 buf[DLN2_I2C_MAX_XFER_SIZE];
83	} __packed *tx = dln2->buf;
84	unsigned len;
85
86	BUILD_BUG_ON(sizeof(*tx) > DLN2_I2C_BUF_SIZE);
87
88	tx->port = dln2->port;
89	tx->addr = addr;
90	tx->mem_addr_len = 0;
91	tx->mem_addr = 0;
92	tx->buf_len = cpu_to_le16(data_len);
93	memcpy(tx->buf, data, data_len);
94
95	len = sizeof(*tx) + data_len - DLN2_I2C_MAX_XFER_SIZE;
96	ret = dln2_transfer_tx(dln2->pdev, DLN2_I2C_WRITE, tx, len);
97	if (ret < 0)
98		return ret;
99
100	return data_len;
101}
102
103static int dln2_i2c_read(struct dln2_i2c *dln2, u16 addr, u8 *data,
104			 u16 data_len)
105{
106	int ret;
107	struct {
108		u8 port;
109		u8 addr;
110		u8 mem_addr_len;
111		__le32 mem_addr;
112		__le16 buf_len;
113	} __packed tx;
114	struct {
115		__le16 buf_len;
116		u8 buf[DLN2_I2C_MAX_XFER_SIZE];
117	} __packed *rx = dln2->buf;
118	unsigned rx_len = sizeof(*rx);
119
120	BUILD_BUG_ON(sizeof(*rx) > DLN2_I2C_BUF_SIZE);
121
122	tx.port = dln2->port;
123	tx.addr = addr;
124	tx.mem_addr_len = 0;
125	tx.mem_addr = 0;
126	tx.buf_len = cpu_to_le16(data_len);
127
128	ret = dln2_transfer(dln2->pdev, DLN2_I2C_READ, &tx, sizeof(tx),
129			    rx, &rx_len);
130	if (ret < 0)
131		return ret;
132	if (rx_len < sizeof(rx->buf_len) + data_len)
133		return -EPROTO;
134	if (le16_to_cpu(rx->buf_len) != data_len)
135		return -EPROTO;
136
137	memcpy(data, rx->buf, data_len);
138
139	return data_len;
140}
141
142static int dln2_i2c_xfer(struct i2c_adapter *adapter,
143			 struct i2c_msg *msgs, int num)
144{
145	struct dln2_i2c *dln2 = i2c_get_adapdata(adapter);
146	struct i2c_msg *pmsg;
147	int i;
148
149	for (i = 0; i < num; i++) {
150		int ret;
151
152		pmsg = &msgs[i];
153
154		if (pmsg->flags & I2C_M_RD) {
155			ret = dln2_i2c_read(dln2, pmsg->addr, pmsg->buf,
156					    pmsg->len);
157			if (ret < 0)
158				return ret;
159
160			pmsg->len = ret;
161		} else {
162			ret = dln2_i2c_write(dln2, pmsg->addr, pmsg->buf,
163					     pmsg->len);
164			if (ret != pmsg->len)
165				return -EPROTO;
166		}
167	}
168
169	return num;
170}
171
172static u32 dln2_i2c_func(struct i2c_adapter *a)
173{
174	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA |
175		I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
176		I2C_FUNC_SMBUS_I2C_BLOCK;
177}
178
179static const struct i2c_algorithm dln2_i2c_usb_algorithm = {
180	.master_xfer = dln2_i2c_xfer,
181	.functionality = dln2_i2c_func,
182};
183
184static struct i2c_adapter_quirks dln2_i2c_quirks = {
185	.max_read_len = DLN2_I2C_MAX_XFER_SIZE,
186	.max_write_len = DLN2_I2C_MAX_XFER_SIZE,
187};
188
189static int dln2_i2c_probe(struct platform_device *pdev)
190{
191	int ret;
192	struct dln2_i2c *dln2;
193	struct device *dev = &pdev->dev;
194	struct dln2_platform_data *pdata = dev_get_platdata(&pdev->dev);
195
196	dln2 = devm_kzalloc(dev, sizeof(*dln2), GFP_KERNEL);
197	if (!dln2)
198		return -ENOMEM;
199
200	dln2->buf = devm_kmalloc(dev, DLN2_I2C_BUF_SIZE, GFP_KERNEL);
201	if (!dln2->buf)
202		return -ENOMEM;
203
204	dln2->pdev = pdev;
205	dln2->port = pdata->port;
206
207	/* setup i2c adapter description */
208	dln2->adapter.owner = THIS_MODULE;
209	dln2->adapter.class = I2C_CLASS_HWMON;
210	dln2->adapter.algo = &dln2_i2c_usb_algorithm;
211	dln2->adapter.quirks = &dln2_i2c_quirks;
212	dln2->adapter.dev.parent = dev;
213	dln2->adapter.dev.of_node = dev->of_node;
214	i2c_set_adapdata(&dln2->adapter, dln2);
215	snprintf(dln2->adapter.name, sizeof(dln2->adapter.name), "%s-%s-%d",
216		 "dln2-i2c", dev_name(pdev->dev.parent), dln2->port);
217
218	platform_set_drvdata(pdev, dln2);
219
220	/* initialize the i2c interface */
221	ret = dln2_i2c_enable(dln2, true);
222	if (ret < 0) {
223		dev_err(dev, "failed to initialize adapter: %d\n", ret);
224		return ret;
225	}
226
227	/* and finally attach to i2c layer */
228	ret = i2c_add_adapter(&dln2->adapter);
229	if (ret < 0) {
230		dev_err(dev, "failed to add I2C adapter: %d\n", ret);
231		goto out_disable;
232	}
233
234	return 0;
235
236out_disable:
237	dln2_i2c_enable(dln2, false);
238
239	return ret;
240}
241
242static int dln2_i2c_remove(struct platform_device *pdev)
243{
244	struct dln2_i2c *dln2 = platform_get_drvdata(pdev);
245
246	i2c_del_adapter(&dln2->adapter);
247	dln2_i2c_enable(dln2, false);
248
249	return 0;
250}
251
252static struct platform_driver dln2_i2c_driver = {
253	.driver.name	= "dln2-i2c",
254	.probe		= dln2_i2c_probe,
255	.remove		= dln2_i2c_remove,
256};
257
258module_platform_driver(dln2_i2c_driver);
259
260MODULE_AUTHOR("Laurentiu Palcu <laurentiu.palcu@intel.com>");
261MODULE_DESCRIPTION("Driver for the Diolan DLN2 I2C master interface");
262MODULE_LICENSE("GPL v2");
263MODULE_ALIAS("platform:dln2-i2c");
264