- 根目录:
- drivers
- nfc
- pn544
- i2c.c
/*
* I2C Link Layer for PN544 HCI based Driver
*
* Copyright (C) 2012 Intel Corporation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the
* Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <linux/crc-ccitt.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/gpio.h>
#include <linux/miscdevice.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/platform_data/pn544.h>
#include <net/nfc/hci.h>
#include <net/nfc/llc.h>
#include "pn544.h"
#define PN544_I2C_FRAME_HEADROOM 1
#define PN544_I2C_FRAME_TAILROOM 2
/* framing in HCI mode */
#define PN544_HCI_I2C_LLC_LEN 1
#define PN544_HCI_I2C_LLC_CRC 2
#define PN544_HCI_I2C_LLC_LEN_CRC (PN544_HCI_I2C_LLC_LEN + \
PN544_HCI_I2C_LLC_CRC)
#define PN544_HCI_I2C_LLC_MIN_SIZE (1 + PN544_HCI_I2C_LLC_LEN_CRC)
#define PN544_HCI_I2C_LLC_MAX_PAYLOAD 29
#define PN544_HCI_I2C_LLC_MAX_SIZE (PN544_HCI_I2C_LLC_LEN_CRC + 1 + \
PN544_HCI_I2C_LLC_MAX_PAYLOAD)
static struct i2c_device_id pn544_hci_i2c_id_table[] = {
{"pn544", 0},
{}
};
MODULE_DEVICE_TABLE(i2c, pn544_hci_i2c_id_table);
#define PN544_HCI_I2C_DRIVER_NAME "pn544_hci_i2c"
struct pn544_i2c_phy {
struct i2c_client *i2c_dev;
struct nfc_hci_dev *hdev;
unsigned int gpio_en;
unsigned int gpio_irq;
unsigned int gpio_fw;
unsigned int en_polarity;
int powered;
int hard_fault; /*
* < 0 if hardware error occured (e.g. i2c err)
* and prevents normal operation.
*/
};
#define I2C_DUMP_SKB(info, skb) \
do { \
pr_debug("%s:\n", info); \
print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
16, 1, (skb)->data, (skb)->len, 0); \
} while (0)
static void pn544_hci_i2c_platform_init(struct pn544_i2c_phy *phy)
{
int polarity, retry, ret;
char rset_cmd[] = { 0x05, 0xF9, 0x04, 0x00, 0xC3, 0xE5 };
int count = sizeof(rset_cmd);
pr_info(DRIVER_DESC ": %s\n", __func__);
dev_info(&phy->i2c_dev->dev, "Detecting nfc_en polarity\n");
/* Disable fw download */
gpio_set_value(phy->gpio_fw, 0);
for (polarity = 0; polarity < 2; polarity++) {
phy->en_polarity = polarity;
retry = 3;
while (retry--) {
/* power off */
gpio_set_value(phy->gpio_en, !phy->en_polarity);
usleep_range(10000, 15000);
/* power on */
gpio_set_value(phy->gpio_en, phy->en_polarity);
usleep_range(10000, 15000);
/* send reset */
dev_dbg(&phy->i2c_dev->dev, "Sending reset cmd\n");
ret = i2c_master_send(phy->i2c_dev, rset_cmd, count);
if (ret == count) {
dev_info(&phy->i2c_dev->dev,
"nfc_en polarity : active %s\n",
(polarity == 0 ? "low" : "high"));
goto out;
}
}
}
dev_err(&phy->i2c_dev->dev,
"Could not detect nfc_en polarity, fallback to active high\n");
out:
gpio_set_value(phy->gpio_en, !phy->en_polarity);
}
static int pn544_hci_i2c_enable(void *phy_id)
{
struct pn544_i2c_phy *phy = phy_id;
pr_info(DRIVER_DESC ": %s\n", __func__);
gpio_set_value(phy->gpio_fw, 0);
gpio_set_value(phy->gpio_en, phy->en_polarity);
usleep_range(10000, 15000);
phy->powered = 1;
return 0;
}
static void pn544_hci_i2c_disable(void *phy_id)
{
struct pn544_i2c_phy *phy = phy_id;
pr_info(DRIVER_DESC ": %s\n", __func__);
gpio_set_value(phy->gpio_fw, 0);
gpio_set_value(phy->gpio_en, !phy->en_polarity);
usleep_range(10000, 15000);
gpio_set_value(phy->gpio_en, phy->en_polarity);
usleep_range(10000, 15000);
gpio_set_value(phy->gpio_en, !phy->en_polarity);
usleep_range(10000, 15000);
phy->powered = 0;
}
static void pn544_hci_i2c_add_len_crc(struct sk_buff *skb)
{
u16 crc;
int len;
len = skb->len + 2;
*skb_push(skb, 1) = len;
crc = crc_ccitt(0xffff, skb->data, skb->len);
crc = ~crc;
*skb_put(skb, 1) = crc & 0xff;
*skb_put(skb, 1) = crc >> 8;
}
static void pn544_hci_i2c_remove_len_crc(struct sk_buff *skb)
{
skb_pull(skb, PN544_I2C_FRAME_HEADROOM);
skb_trim(skb, PN544_I2C_FRAME_TAILROOM);
}
/*
* Writing a frame must not return the number of written bytes.
* It must return either zero for success, or <0 for error.
* In addition, it must not alter the skb
*/
static int pn544_hci_i2c_write(void *phy_id, struct sk_buff *skb)
{
int r;
struct pn544_i2c_phy *phy = phy_id;
struct i2c_client *client = phy->i2c_dev;
if (phy->hard_fault != 0)
return phy->hard_fault;
usleep_range(3000, 6000);
pn544_hci_i2c_add_len_crc(skb);
I2C_DUMP_SKB("i2c frame written", skb);
r = i2c_master_send(client, skb->data, skb->len);
if (r == -EREMOTEIO) { /* Retry, chip was in standby */
usleep_range(6000, 10000);
r = i2c_master_send(client, skb->data, skb->len);
}
if (r >= 0) {
if (r != skb->len)
r = -EREMOTEIO;
else
r = 0;
}
pn544_hci_i2c_remove_len_crc(skb);
return r;
}
static int check_crc(u8 *buf, int buflen)
{
int len;
u16 crc;
len = buf[0] + 1;
crc = crc_ccitt(0xffff, buf, len - 2);
crc = ~crc;
if (buf[len - 2] != (crc & 0xff) || buf[len - 1] != (crc >> 8)) {
pr_err(PN544_HCI_I2C_DRIVER_NAME
": CRC error 0x%x != 0x%x 0x%x\n",
crc, buf[len - 1], buf[len - 2]);
pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
16, 2, buf, buflen, false);
return -EPERM;
}
return 0;
}
/*
* Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
* that i2c bus will be flushed and that next read will start on a new frame.
* returned skb contains only LLC header and payload.
* returns:
* -EREMOTEIO : i2c read error (fatal)
* -EBADMSG : frame was incorrect and discarded
* -ENOMEM : cannot allocate skb, frame dropped
*/
static int pn544_hci_i2c_read(struct pn544_i2c_phy *phy, struct sk_buff **skb)
{
int r;
u8 len;
u8 tmp[PN544_HCI_I2C_LLC_MAX_SIZE - 1];
struct i2c_client *client = phy->i2c_dev;
r = i2c_master_recv(client, &len, 1);
if (r != 1) {
dev_err(&client->dev, "cannot read len byte\n");
return -EREMOTEIO;
}
if ((len < (PN544_HCI_I2C_LLC_MIN_SIZE - 1)) ||
(len > (PN544_HCI_I2C_LLC_MAX_SIZE - 1))) {
dev_err(&client->dev, "invalid len byte\n");
r = -EBADMSG;
goto flush;
}
*skb = alloc_skb(1 + len, GFP_KERNEL);
if (*skb == NULL) {
r = -ENOMEM;
goto flush;
}
*skb_put(*skb, 1) = len;
r = i2c_master_recv(client, skb_put(*skb, len), len);
if (r != len) {
kfree_skb(*skb);
return -EREMOTEIO;
}
I2C_DUMP_SKB("i2c frame read", *skb);
r = check_crc((*skb)->data, (*skb)->len);
if (r != 0) {
kfree_skb(*skb);
r = -EBADMSG;
goto flush;
}
skb_pull(*skb, 1);
skb_trim(*skb, (*skb)->len - 2);
usleep_range(3000, 6000);
return 0;
flush:
if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
r = -EREMOTEIO;
usleep_range(3000, 6000);
return r;
}
/*
* Reads an shdlc frame from the chip. This is not as straightforward as it
* seems. There are cases where we could loose the frame start synchronization.
* The frame format is len-data-crc, and corruption can occur anywhere while
* transiting on i2c bus, such that we could read an invalid len.
* In order to recover synchronization with the next frame, we must be sure
* to read the real amount of data without using the len byte. We do this by
* assuming the following:
* - the chip will always present only one single complete frame on the bus
* before triggering the interrupt
* - the chip will not present a new frame until we have completely read
* the previous one (or until we have handled the interrupt).
* The tricky case is when we read a corrupted len that is less than the real
* len. We must detect this here in order to determine that we need to flush
* the bus. This is the reason why we check the crc here.
*/
static irqreturn_t pn544_hci_i2c_irq_thread_fn(int irq, void *phy_id)
{
struct pn544_i2c_phy *phy = phy_id;
struct i2c_client *client;
struct sk_buff *skb = NULL;
int r;
if (!phy || irq != phy->i2c_dev->irq) {
WARN_ON_ONCE(1);
return IRQ_NONE;
}
client = phy->i2c_dev;
dev_dbg(&client->dev, "IRQ\n");
if (phy->hard_fault != 0)
return IRQ_HANDLED;
r = pn544_hci_i2c_read(phy, &skb);
if (r == -EREMOTEIO) {
phy->hard_fault = r;
nfc_hci_recv_frame(phy->hdev, NULL);
return IRQ_HANDLED;
} else if ((r == -ENOMEM) || (r == -EBADMSG)) {
return IRQ_HANDLED;
}
nfc_hci_recv_frame(phy->hdev, skb);
return IRQ_HANDLED;
}
static struct nfc_phy_ops i2c_phy_ops = {
.write = pn544_hci_i2c_write,
.enable = pn544_hci_i2c_enable,
.disable = pn544_hci_i2c_disable,
};
static int pn544_hci_i2c_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct pn544_i2c_phy *phy;
struct pn544_nfc_platform_data *pdata;
int r = 0;
dev_dbg(&client->dev, "%s\n", __func__);
dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
dev_err(&client->dev, "Need I2C_FUNC_I2C\n");
return -ENODEV;
}
phy = devm_kzalloc(&client->dev, sizeof(struct pn544_i2c_phy),
GFP_KERNEL);
if (!phy) {
dev_err(&client->dev,
"Cannot allocate memory for pn544 i2c phy.\n");
return -ENOMEM;
}
phy->i2c_dev = client;
i2c_set_clientdata(client, phy);
pdata = client->dev.platform_data;
if (pdata == NULL) {
dev_err(&client->dev, "No platform data\n");
return -EINVAL;
}
if (pdata->request_resources == NULL) {
dev_err(&client->dev, "request_resources() missing\n");
return -EINVAL;
}
r = pdata->request_resources(client);
if (r) {
dev_err(&client->dev, "Cannot get platform resources\n");
return r;
}
phy->gpio_en = pdata->get_gpio(NFC_GPIO_ENABLE);
phy->gpio_fw = pdata->get_gpio(NFC_GPIO_FW_RESET);
phy->gpio_irq = pdata->get_gpio(NFC_GPIO_IRQ);
pn544_hci_i2c_platform_init(phy);
r = request_threaded_irq(client->irq, NULL, pn544_hci_i2c_irq_thread_fn,
IRQF_TRIGGER_RISING | IRQF_ONESHOT,
PN544_HCI_I2C_DRIVER_NAME, phy);
if (r < 0) {
dev_err(&client->dev, "Unable to register IRQ handler\n");
goto err_rti;
}
r = pn544_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
PN544_I2C_FRAME_HEADROOM, PN544_I2C_FRAME_TAILROOM,
PN544_HCI_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
if (r < 0)
goto err_hci;
return 0;
err_hci:
free_irq(client->irq, phy);
err_rti:
if (pdata->free_resources != NULL)
pdata->free_resources();
return r;
}
static int pn544_hci_i2c_remove(struct i2c_client *client)
{
struct pn544_i2c_phy *phy = i2c_get_clientdata(client);
struct pn544_nfc_platform_data *pdata = client->dev.platform_data;
dev_dbg(&client->dev, "%s\n", __func__);
pn544_hci_remove(phy->hdev);
if (phy->powered)
pn544_hci_i2c_disable(phy);
free_irq(client->irq, phy);
if (pdata->free_resources)
pdata->free_resources();
return 0;
}
static struct i2c_driver pn544_hci_i2c_driver = {
.driver = {
.name = PN544_HCI_I2C_DRIVER_NAME,
},
.probe = pn544_hci_i2c_probe,
.id_table = pn544_hci_i2c_id_table,
.remove = pn544_hci_i2c_remove,
};
module_i2c_driver(pn544_hci_i2c_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(DRIVER_DESC);