#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/gpio.h>
#include <linux/nfc.h>
#include <net/nfc/hci.h>
#include <net/nfc/llc.h>
#include "microread.h"
#define MICROREAD_I2C_DRIVER_NAME "microread"
#define MICROREAD_I2C_FRAME_HEADROOM 1
#define MICROREAD_I2C_FRAME_TAILROOM 1
#define MICROREAD_I2C_LLC_LEN 1
#define MICROREAD_I2C_LLC_CRC 1
#define MICROREAD_I2C_LLC_LEN_CRC (MICROREAD_I2C_LLC_LEN + \
MICROREAD_I2C_LLC_CRC)
#define MICROREAD_I2C_LLC_MIN_SIZE (1 + MICROREAD_I2C_LLC_LEN_CRC)
#define MICROREAD_I2C_LLC_MAX_PAYLOAD 29
#define MICROREAD_I2C_LLC_MAX_SIZE (MICROREAD_I2C_LLC_LEN_CRC + 1 + \
MICROREAD_I2C_LLC_MAX_PAYLOAD)
struct microread_i2c_phy {
struct i2c_client *i2c_dev;
struct nfc_hci_dev *hdev;
int hard_fault;
};
#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 microread_i2c_add_len_crc(struct sk_buff *skb)
{
int i;
u8 crc = 0;
int len;
len = skb->len;
*(u8 *)skb_push(skb, 1) = len;
for (i = 0; i < skb->len; i++)
crc = crc ^ skb->data[i];
skb_put_u8(skb, crc);
}
static void microread_i2c_remove_len_crc(struct sk_buff *skb)
{
skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
}
static int check_crc(const struct sk_buff *skb)
{
int i;
u8 crc = 0;
for (i = 0; i < skb->len - 1; i++)
crc = crc ^ skb->data[i];
if (crc != skb->data[skb->len-1]) {
pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]);
pr_info("%s: BAD CRC\n", __func__);
return -EPERM;
}
return 0;
}
static int microread_i2c_enable(void *phy_id)
{
return 0;
}
static void microread_i2c_disable(void *phy_id)
{
return;
}
static int microread_i2c_write(void *phy_id, struct sk_buff *skb)
{
int r;
struct microread_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);
microread_i2c_add_len_crc(skb);
I2C_DUMP_SKB("i2c frame written", skb);
r = i2c_master_send(client, skb->data, skb->len);
if (r == -EREMOTEIO) {
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;
}
microread_i2c_remove_len_crc(skb);
return r;
}
static int microread_i2c_read(struct microread_i2c_phy *phy,
struct sk_buff **skb)
{
int r;
u8 len;
u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
struct i2c_client *client = phy->i2c_dev;
r = i2c_master_recv(client, &len, 1);
if (r != 1) {
nfc_err(&client->dev, "cannot read len byte\n");
return -EREMOTEIO;
}
if ((len < MICROREAD_I2C_LLC_MIN_SIZE) ||
(len > MICROREAD_I2C_LLC_MAX_SIZE)) {
nfc_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_u8(*skb, len);
r = i2c_master_recv(client, skb_put(*skb, len), len);
if (r != len) {
kfree_skb(*skb);
return -EREMOTEIO;
}
I2C_DUMP_SKB("cc frame read", *skb);
r = check_crc(*skb);
if (r != 0) {
kfree_skb(*skb);
r = -EBADMSG;
goto flush;
}
skb_pull(*skb, 1);
skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM);
usleep_range(3000, 6000);
return 0;
flush:
if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
r = -EREMOTEIO;
usleep_range(3000, 6000);
return r;
}
static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
{
struct microread_i2c_phy *phy = phy_id;
struct sk_buff *skb = NULL;
int r;
if (!phy || irq != phy->i2c_dev->irq) {
WARN_ON_ONCE(1);
return IRQ_NONE;
}
if (phy->hard_fault != 0)
return IRQ_HANDLED;
r = microread_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 const struct nfc_phy_ops i2c_phy_ops = {
.write = microread_i2c_write,
.enable = microread_i2c_enable,
.disable = microread_i2c_disable,
};
static int microread_i2c_probe(struct i2c_client *client)
{
struct microread_i2c_phy *phy;
int r;
phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
GFP_KERNEL);
if (!phy)
return -ENOMEM;
i2c_set_clientdata(client, phy);
phy->i2c_dev = client;
r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
IRQF_TRIGGER_RISING | IRQF_ONESHOT,
MICROREAD_I2C_DRIVER_NAME, phy);
if (r) {
nfc_err(&client->dev, "Unable to register IRQ handler\n");
return r;
}
r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
MICROREAD_I2C_FRAME_HEADROOM,
MICROREAD_I2C_FRAME_TAILROOM,
MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
if (r < 0)
goto err_irq;
return 0;
err_irq:
free_irq(client->irq, phy);
return r;
}
static void microread_i2c_remove(struct i2c_client *client)
{
struct microread_i2c_phy *phy = i2c_get_clientdata(client);
microread_remove(phy->hdev);
free_irq(client->irq, phy);
}
static const struct i2c_device_id microread_i2c_id[] = {
{ MICROREAD_I2C_DRIVER_NAME },
{ }
};
MODULE_DEVICE_TABLE(i2c, microread_i2c_id);
static struct i2c_driver microread_i2c_driver = {
.driver = {
.name = MICROREAD_I2C_DRIVER_NAME,
},
.probe = microread_i2c_probe,
.remove = microread_i2c_remove,
.id_table = microread_i2c_id,
};
module_i2c_driver(microread_i2c_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(DRIVER_DESC);
