// SPDX-License-Identifier: GPL-2.0-only
/*
* I2C Link Layer for ST21NFCA HCI based Driver
* Copyright (C) 2014 STMicroelectronics SAS. All rights reserved.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/crc-ccitt.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/gpio/consumer.h>
#include <linux/of_irq.h>
#include <linux/of_gpio.h>
#include <linux/acpi.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/nfc.h>
#include <linux/firmware.h>
#include <net/nfc/hci.h>
#include <net/nfc/llc.h>
#include <net/nfc/nfc.h>
#include "st21nfca.h"
/*
* Every frame starts with ST21NFCA_SOF_EOF and ends with ST21NFCA_SOF_EOF.
* Because ST21NFCA_SOF_EOF is a possible data value, there is a mecanism
* called byte stuffing has been introduced.
*
* if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
* - insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
* - xor byte with ST21NFCA_BYTE_STUFFING_MASK
*/
#define ST21NFCA_SOF_EOF 0x7e
#define ST21NFCA_BYTE_STUFFING_MASK 0x20
#define ST21NFCA_ESCAPE_BYTE_STUFFING 0x7d
/* SOF + 00 */
#define ST21NFCA_FRAME_HEADROOM 2
/* 2 bytes crc + EOF */
#define ST21NFCA_FRAME_TAILROOM 3
#define IS_START_OF_FRAME(buf) (buf[0] == ST21NFCA_SOF_EOF && \
buf[1] == 0)
#define ST21NFCA_HCI_DRIVER_NAME "st21nfca_hci"
#define ST21NFCA_HCI_I2C_DRIVER_NAME "st21nfca_hci_i2c"
struct st21nfca_i2c_phy {
struct i2c_client *i2c_dev;
struct nfc_hci_dev *hdev;
struct gpio_desc *gpiod_ena;
struct st21nfca_se_status se_status;
struct sk_buff *pending_skb;
int current_read_len;
/*
* crc might have fail because i2c macro
* is disable due to other interface activity
*/
int crc_trials;
int powered;
int run_mode;
/*
* < 0 if hardware error occured (e.g. i2c err)
* and prevents normal operation.
*/
int hard_fault;
struct mutex phy_lock;
};
static const u8 len_seq[] = { 16, 24, 12, 29 };
static const u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};
#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)
/*
* In order to get the CLF in a known state we generate an internal reboot
* using a proprietary command.
* Once the reboot is completed, we expect to receive a ST21NFCA_SOF_EOF
* fill buffer.
*/
static int st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy)
{
u16 wait_reboot[] = { 50, 300, 1000 };
char reboot_cmd[] = { 0x7E, 0x66, 0x48, 0xF6, 0x7E };
u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE];
int i, r = -1;
for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
r = i2c_master_send(phy->i2c_dev, reboot_cmd,
sizeof(reboot_cmd));
if (r < 0)
msleep(wait_reboot[i]);
}
if (r < 0)
return r;
/* CLF is spending about 20ms to do an internal reboot */
msleep(20);
r = -1;
for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
r = i2c_master_recv(phy->i2c_dev, tmp,
ST21NFCA_HCI_LLC_MAX_SIZE);
if (r < 0)
msleep(wait_reboot[i]);
}
if (r < 0)
return r;
for (i = 0; i < ST21NFCA_HCI_LLC_MAX_SIZE &&
tmp[i] == ST21NFCA_SOF_EOF; i++)
;
if (r != ST21NFCA_HCI_LLC_MAX_SIZE)
return -ENODEV;
usleep_range(1000, 1500);
return 0;
}
static int st21nfca_hci_i2c_enable(void *phy_id)
{
struct st21nfca_i2c_phy *phy = phy_id;
gpiod_set_value(phy->gpiod_ena, 1);
phy->powered = 1;
phy->run_mode = ST21NFCA_HCI_MODE;
usleep_range(10000, 15000);
return 0;
}
static void st21nfca_hci_i2c_disable(void *phy_id)
{
struct st21nfca_i2c_phy *phy = phy_id;
gpiod_set_value(phy->gpiod_ena, 0);
phy->powered = 0;
}
static void st21nfca_hci_add_len_crc(struct sk_buff *skb)
{
u16 crc;
u8 tmp;
*(u8 *)skb_push(skb, 1) = 0;
crc = crc_ccitt(0xffff, skb->data, skb->len);
crc = ~crc;
tmp = crc & 0x00ff;
skb_put_u8(skb, tmp);
tmp = (crc >> 8) & 0x00ff;
skb_put_u8(skb, tmp);
}
static void st21nfca_hci_remove_len_crc(struct sk_buff *skb)
{
skb_pull(skb, ST21NFCA_FRAME_HEADROOM);
skb_trim(skb, skb->len - ST21NFCA_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 st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb)
{
int r = -1, i, j;
struct st21nfca_i2c_phy *phy = phy_id;
struct i2c_client *client = phy->i2c_dev;
u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE * 2];
I2C_DUMP_SKB("st21nfca_hci_i2c_write", skb);
if (phy->hard_fault != 0)
return phy->hard_fault;
/*
* Compute CRC before byte stuffing computation on frame
* Note st21nfca_hci_add_len_crc is doing a byte stuffing
* on its own value
*/
st21nfca_hci_add_len_crc(skb);
/* add ST21NFCA_SOF_EOF on tail */
skb_put_u8(skb, ST21NFCA_SOF_EOF);
/* add ST21NFCA_SOF_EOF on head */
*(u8 *)skb_push(skb, 1) = ST21NFCA_SOF_EOF;
/*
* Compute byte stuffing
* if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
* insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
* xor byte with ST21NFCA_BYTE_STUFFING_MASK
*/
tmp[0] = skb->data[0];
for (i = 1, j = 1; i < skb->len - 1; i++, j++) {
if (skb->data[i] == ST21NFCA_SOF_EOF
|| skb->data[i] == ST21NFCA_ESCAPE_BYTE_STUFFING) {
tmp[j] = ST21NFCA_ESCAPE_BYTE_STUFFING;
j++;
tmp[j] = skb->data[i] ^ ST21NFCA_BYTE_STUFFING_MASK;
} else {
tmp[j] = skb->data[i];
}
}
tmp[j] = skb->data[i];
j++;
/*
* Manage sleep mode
* Try 3 times to send data with delay between each
*/
mutex_lock(&phy->phy_lock);
for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++) {
r = i2c_master_send(client, tmp, j);
if (r < 0)
msleep(wait_tab[i]);
}
mutex_unlock(&phy->phy_lock);
if (r >= 0) {
if (r != j)
r = -EREMOTEIO;
else
r = 0;
}
st21nfca_hci_remove_len_crc(skb);
return r;
}
static int get_frame_size(u8 *buf, int buflen)
{
int len = 0;
if (buf[len + 1] == ST21NFCA_SOF_EOF)
return 0;
for (len = 1; len < buflen && buf[len] != ST21NFCA_SOF_EOF; len++)
;
return len;
}
static int check_crc(u8 *buf, int buflen)
{
u16 crc;
crc = crc_ccitt(0xffff, buf, buflen - 2);
crc = ~crc;
if (buf[buflen - 2] != (crc & 0xff) || buf[buflen - 1] != (crc >> 8)) {
pr_err(ST21NFCA_HCI_DRIVER_NAME
": CRC error 0x%x != 0x%x 0x%x\n", crc, buf[buflen - 1],
buf[buflen - 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;
}
/*
* Prepare received data for upper layer.
* Received data include byte stuffing, crc and sof/eof
* which is not usable by hci part.
* returns:
* frame size without sof/eof, header and byte stuffing
* -EBADMSG : frame was incorrect and discarded
*/
static int st21nfca_hci_i2c_repack(struct sk_buff *skb)
{
int i, j, r, size;
if (skb->len < 1 || (skb->len > 1 && skb->data[1] != 0))
return -EBADMSG;
size = get_frame_size(skb->data, skb->len);
if (size > 0) {
skb_trim(skb, size);
/* remove ST21NFCA byte stuffing for upper layer */
for (i = 1, j = 0; i < skb->len; i++) {
if (skb->data[i + j] ==
(u8) ST21NFCA_ESCAPE_BYTE_STUFFING) {
skb->data[i] = skb->data[i + j + 1]
| ST21NFCA_BYTE_STUFFING_MASK;
i++;
j++;
}
skb->data[i] = skb->data[i + j];
}
/* remove byte stuffing useless byte */
skb_trim(skb, i - j);
/* remove ST21NFCA_SOF_EOF from head */
skb_pull(skb, 1);
r = check_crc(skb->data, skb->len);
if (r != 0)
return -EBADMSG;
/* remove headbyte */
skb_pull(skb, 1);
/* remove crc. Byte Stuffing is already removed here */
skb_trim(skb, skb->len - 2);
return skb->len;
}
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:
* frame size : if received frame is complete (find ST21NFCA_SOF_EOF at
* end of read)
* -EAGAIN : if received frame is incomplete (not find ST21NFCA_SOF_EOF
* at end of read)
* -EREMOTEIO : i2c read error (fatal)
* -EBADMSG : frame was incorrect and discarded
* (value returned from st21nfca_hci_i2c_repack)
* -EIO : if no ST21NFCA_SOF_EOF is found after reaching
* the read length end sequence
*/
static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy,
struct sk_buff *skb)
{
int r, i;
u8 len;
u8 buf[ST21NFCA_HCI_LLC_MAX_PAYLOAD];
struct i2c_client *client = phy->i2c_dev;
if (phy->current_read_len < ARRAY_SIZE(len_seq)) {
len = len_seq[phy->current_read_len];
/*
* Add retry mecanism
* Operation on I2C interface may fail in case of operation on
* RF or SWP interface
*/
r = 0;
mutex_lock(&phy->phy_lock);
for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) {
r = i2c_master_recv(client, buf, len);
if (r < 0)
msleep(wait_tab[i]);
}
mutex_unlock(&phy->phy_lock);
if (r != len) {
phy->current_read_len = 0;
return -EREMOTEIO;
}
/*
* The first read sequence does not start with SOF.
* Data is corrupeted so we drop it.
*/
if (!phy->current_read_len && !IS_START_OF_FRAME(buf)) {
skb_trim(skb, 0);
phy->current_read_len = 0;
return -EIO;
} else if (phy->current_read_len && IS_START_OF_FRAME(buf)) {
/*
* Previous frame transmission was interrupted and
* the frame got repeated.
* Received frame start with ST21NFCA_SOF_EOF + 00.
*/
skb_trim(skb, 0);
phy->current_read_len = 0;
}
skb_put_data(skb, buf, len);
if (skb->data[skb->len - 1] == ST21NFCA_SOF_EOF) {
phy->current_read_len = 0;
return st21nfca_hci_i2c_repack(skb);
}
phy->current_read_len++;
return -EAGAIN;
}
return -EIO;
}
/*
* Reads an shdlc frame from the chip. This is not as straightforward as it
* seems. The frame format is data-crc, and corruption can occur anywhere
* while transiting on i2c bus, such that we could read an invalid data.
* The tricky case is when we read a corrupted data or crc. We must detect
* this here in order to determine that data can be transmitted to the hci
* core. This is the reason why we check the crc here.
* The CLF will repeat a frame until we send a RR on that frame.
*
* On ST21NFCA, IRQ goes in idle when read starts. As no size information are
* available in the incoming data, other IRQ might come. Every IRQ will trigger
* a read sequence with different length and will fill the current frame.
* The reception is complete once we reach a ST21NFCA_SOF_EOF.
*/
static irqreturn_t st21nfca_hci_irq_thread_fn(int irq, void *phy_id)
{
struct st21nfca_i2c_phy *phy = phy_id;
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 = st21nfca_hci_i2c_read(phy, phy->pending_skb);
if (r == -EREMOTEIO) {
phy->hard_fault = r;
nfc_hci_recv_frame(phy->hdev, NULL);
return IRQ_HANDLED;
} else if (r == -EAGAIN || r == -EIO) {
return IRQ_HANDLED;
} else if (r == -EBADMSG && phy->crc_trials < ARRAY_SIZE(wait_tab)) {
/*
* With ST21NFCA, only one interface (I2C, RF or SWP)
* may be active at a time.
* Having incorrect crc is usually due to i2c macrocell
* deactivation in the middle of a transmission.
* It may generate corrupted data on i2c.
* We give sometime to get i2c back.
* The complete frame will be repeated.
*/
msleep(wait_tab[phy->crc_trials]);
phy->crc_trials++;
phy->current_read_len = 0;
kfree_skb(phy->pending_skb);
} else if (r > 0) {
/*
* We succeeded to read data from the CLF and
* data is valid.
* Reset counter.
*/
nfc_hci_recv_frame(phy->hdev, phy->pending_skb);
phy->crc_trials = 0;
} else {
kfree_skb(phy->pending_skb);
}
phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
if (phy->pending_skb == NULL) {
phy->hard_fault = -ENOMEM;
nfc_hci_recv_frame(phy->hdev, NULL);
}
return IRQ_HANDLED;
}
static const struct nfc_phy_ops i2c_phy_ops = {
.write = st21nfca_hci_i2c_write,
.enable = st21nfca_hci_i2c_enable,
.disable = st21nfca_hci_i2c_disable,
};
static const struct acpi_gpio_params enable_gpios = { 1, 0, false };
static const struct acpi_gpio_mapping acpi_st21nfca_gpios[] = {
{ "enable-gpios", &enable_gpios, 1 },
{},
};
static int st21nfca_hci_i2c_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct st21nfca_i2c_phy *phy;
int r;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
return -ENODEV;
}
phy = devm_kzalloc(&client->dev, sizeof(struct st21nfca_i2c_phy),
GFP_KERNEL);
if (!phy)
return -ENOMEM;
phy->i2c_dev = client;
phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
if (phy->pending_skb == NULL)
return -ENOMEM;
phy->current_read_len = 0;
phy->crc_trials = 0;
mutex_init(&phy->phy_lock);
i2c_set_clientdata(client, phy);
r = devm_acpi_dev_add_driver_gpios(dev, acpi_st21nfca_gpios);
if (r)
dev_dbg(dev, "Unable to add GPIO mapping table\n");
/* Get EN GPIO from resource provider */
phy->gpiod_ena = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
if (IS_ERR(phy->gpiod_ena)) {
nfc_err(dev, "Unable to get ENABLE GPIO\n");
r = PTR_ERR(phy->gpiod_ena);
goto out_free;
}
phy->se_status.is_ese_present =
device_property_read_bool(&client->dev, "ese-present");
phy->se_status.is_uicc_present =
device_property_read_bool(&client->dev, "uicc-present");
r = st21nfca_hci_platform_init(phy);
if (r < 0) {
nfc_err(&client->dev, "Unable to reboot st21nfca\n");
goto out_free;
}
r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
st21nfca_hci_irq_thread_fn,
IRQF_ONESHOT,
ST21NFCA_HCI_DRIVER_NAME, phy);
if (r < 0) {
nfc_err(&client->dev, "Unable to register IRQ handler\n");
goto out_free;
}
r = st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
ST21NFCA_FRAME_HEADROOM,
ST21NFCA_FRAME_TAILROOM,
ST21NFCA_HCI_LLC_MAX_PAYLOAD,
&phy->hdev,
&phy->se_status);
if (r)
goto out_free;
return 0;
out_free:
kfree_skb(phy->pending_skb);
return r;
}
static void st21nfca_hci_i2c_remove(struct i2c_client *client)
{
struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);
st21nfca_hci_remove(phy->hdev);
if (phy->powered)
st21nfca_hci_i2c_disable(phy);
kfree_skb(phy->pending_skb);
}
static const struct i2c_device_id st21nfca_hci_i2c_id_table[] = {
{ ST21NFCA_HCI_DRIVER_NAME },
{}
};
MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table);
static const struct acpi_device_id st21nfca_hci_i2c_acpi_match[] __maybe_unused = {
{"SMO2100", 0},
{}
};
MODULE_DEVICE_TABLE(acpi, st21nfca_hci_i2c_acpi_match);
static const struct of_device_id of_st21nfca_i2c_match[] __maybe_unused = {
{ .compatible = "st,st21nfca-i2c", },
{ .compatible = "st,st21nfca_i2c", },
{}
};
MODULE_DEVICE_TABLE(of, of_st21nfca_i2c_match);
static struct i2c_driver st21nfca_hci_i2c_driver = {
.driver = {
.name = ST21NFCA_HCI_I2C_DRIVER_NAME,
.of_match_table = of_match_ptr(of_st21nfca_i2c_match),
.acpi_match_table = ACPI_PTR(st21nfca_hci_i2c_acpi_match),
},
.probe = st21nfca_hci_i2c_probe,
.id_table = st21nfca_hci_i2c_id_table,
.remove = st21nfca_hci_i2c_remove,
};
module_i2c_driver(st21nfca_hci_i2c_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(DRIVER_DESC);
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