linux/drivers/nfc/st-nci/i2c.c
Colin Ian King 23ec8eaf46 nfc: st-nci: remove redundant assignment to variable r
The variable r is being initialized with a value that is never
read and it is being updated later with a new value. The
initialization is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-07-02 12:00:50 -07:00

306 lines
6.9 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* I2C Link Layer for ST NCI NFC controller familly based Driver
* Copyright (C) 2014-2015 STMicroelectronics SAS. All rights reserved.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/gpio/consumer.h>
#include <linux/acpi.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/nfc.h>
#include <linux/of.h>
#include "st-nci.h"
#define DRIVER_DESC "NCI NFC driver for ST_NCI"
/* ndlc header */
#define ST_NCI_FRAME_HEADROOM 1
#define ST_NCI_FRAME_TAILROOM 0
#define ST_NCI_I2C_MIN_SIZE 4 /* PCB(1) + NCI Packet header(3) */
#define ST_NCI_I2C_MAX_SIZE 250 /* req 4.2.1 */
#define ST_NCI_DRIVER_NAME "st_nci"
#define ST_NCI_I2C_DRIVER_NAME "st_nci_i2c"
struct st_nci_i2c_phy {
struct i2c_client *i2c_dev;
struct llt_ndlc *ndlc;
bool irq_active;
struct gpio_desc *gpiod_reset;
struct st_nci_se_status se_status;
};
static int st_nci_i2c_enable(void *phy_id)
{
struct st_nci_i2c_phy *phy = phy_id;
gpiod_set_value(phy->gpiod_reset, 0);
usleep_range(10000, 15000);
gpiod_set_value(phy->gpiod_reset, 1);
usleep_range(80000, 85000);
if (phy->ndlc->powered == 0 && phy->irq_active == 0) {
enable_irq(phy->i2c_dev->irq);
phy->irq_active = true;
}
return 0;
}
static void st_nci_i2c_disable(void *phy_id)
{
struct st_nci_i2c_phy *phy = phy_id;
disable_irq_nosync(phy->i2c_dev->irq);
phy->irq_active = false;
}
/*
* 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 st_nci_i2c_write(void *phy_id, struct sk_buff *skb)
{
int r;
struct st_nci_i2c_phy *phy = phy_id;
struct i2c_client *client = phy->i2c_dev;
if (phy->ndlc->hard_fault != 0)
return phy->ndlc->hard_fault;
r = i2c_master_send(client, skb->data, skb->len);
if (r < 0) { /* Retry, chip was in standby */
usleep_range(1000, 4000);
r = i2c_master_send(client, skb->data, skb->len);
}
if (r >= 0) {
if (r != skb->len)
r = -EREMOTEIO;
else
r = 0;
}
return r;
}
/*
* Reads an ndlc frame and returns it in a newly allocated sk_buff.
* returns:
* 0 : if received frame is complete
* -EREMOTEIO : i2c read error (fatal)
* -EBADMSG : frame was incorrect and discarded
* -ENOMEM : cannot allocate skb, frame dropped
*/
static int st_nci_i2c_read(struct st_nci_i2c_phy *phy,
struct sk_buff **skb)
{
int r;
u8 len;
u8 buf[ST_NCI_I2C_MAX_SIZE];
struct i2c_client *client = phy->i2c_dev;
r = i2c_master_recv(client, buf, ST_NCI_I2C_MIN_SIZE);
if (r < 0) { /* Retry, chip was in standby */
usleep_range(1000, 4000);
r = i2c_master_recv(client, buf, ST_NCI_I2C_MIN_SIZE);
}
if (r != ST_NCI_I2C_MIN_SIZE)
return -EREMOTEIO;
len = be16_to_cpu(*(__be16 *) (buf + 2));
if (len > ST_NCI_I2C_MAX_SIZE) {
nfc_err(&client->dev, "invalid frame len\n");
return -EBADMSG;
}
*skb = alloc_skb(ST_NCI_I2C_MIN_SIZE + len, GFP_KERNEL);
if (*skb == NULL)
return -ENOMEM;
skb_reserve(*skb, ST_NCI_I2C_MIN_SIZE);
skb_put(*skb, ST_NCI_I2C_MIN_SIZE);
memcpy((*skb)->data, buf, ST_NCI_I2C_MIN_SIZE);
if (!len)
return 0;
r = i2c_master_recv(client, buf, len);
if (r != len) {
kfree_skb(*skb);
return -EREMOTEIO;
}
skb_put(*skb, len);
memcpy((*skb)->data + ST_NCI_I2C_MIN_SIZE, buf, len);
return 0;
}
/*
* Reads an ndlc frame from the chip.
*
* On ST_NCI, IRQ goes in idle state when read starts.
*/
static irqreturn_t st_nci_irq_thread_fn(int irq, void *phy_id)
{
struct st_nci_i2c_phy *phy = phy_id;
struct i2c_client *client;
struct sk_buff *skb = NULL;
int r;
if (!phy || !phy->ndlc || irq != phy->i2c_dev->irq) {
WARN_ON_ONCE(1);
return IRQ_NONE;
}
client = phy->i2c_dev;
dev_dbg(&client->dev, "IRQ\n");
if (phy->ndlc->hard_fault)
return IRQ_HANDLED;
if (!phy->ndlc->powered) {
st_nci_i2c_disable(phy);
return IRQ_HANDLED;
}
r = st_nci_i2c_read(phy, &skb);
if (r == -EREMOTEIO || r == -ENOMEM || r == -EBADMSG)
return IRQ_HANDLED;
ndlc_recv(phy->ndlc, skb);
return IRQ_HANDLED;
}
static struct nfc_phy_ops i2c_phy_ops = {
.write = st_nci_i2c_write,
.enable = st_nci_i2c_enable,
.disable = st_nci_i2c_disable,
};
static const struct acpi_gpio_params reset_gpios = { 1, 0, false };
static const struct acpi_gpio_mapping acpi_st_nci_gpios[] = {
{ "reset-gpios", &reset_gpios, 1 },
{},
};
static int st_nci_i2c_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct device *dev = &client->dev;
struct st_nci_i2c_phy *phy;
int r;
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)) {
nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
return -ENODEV;
}
phy = devm_kzalloc(dev, sizeof(struct st_nci_i2c_phy), GFP_KERNEL);
if (!phy)
return -ENOMEM;
phy->i2c_dev = client;
i2c_set_clientdata(client, phy);
r = devm_acpi_dev_add_driver_gpios(dev, acpi_st_nci_gpios);
if (r)
dev_dbg(dev, "Unable to add GPIO mapping table\n");
/* Get RESET GPIO */
phy->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
if (IS_ERR(phy->gpiod_reset)) {
nfc_err(dev, "Unable to get RESET GPIO\n");
return -ENODEV;
}
phy->se_status.is_ese_present =
device_property_read_bool(dev, "ese-present");
phy->se_status.is_uicc_present =
device_property_read_bool(dev, "uicc-present");
r = ndlc_probe(phy, &i2c_phy_ops, &client->dev,
ST_NCI_FRAME_HEADROOM, ST_NCI_FRAME_TAILROOM,
&phy->ndlc, &phy->se_status);
if (r < 0) {
nfc_err(&client->dev, "Unable to register ndlc layer\n");
return r;
}
phy->irq_active = true;
r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
st_nci_irq_thread_fn,
IRQF_ONESHOT,
ST_NCI_DRIVER_NAME, phy);
if (r < 0)
nfc_err(&client->dev, "Unable to register IRQ handler\n");
return r;
}
static int st_nci_i2c_remove(struct i2c_client *client)
{
struct st_nci_i2c_phy *phy = i2c_get_clientdata(client);
dev_dbg(&client->dev, "%s\n", __func__);
ndlc_remove(phy->ndlc);
return 0;
}
static const struct i2c_device_id st_nci_i2c_id_table[] = {
{ST_NCI_DRIVER_NAME, 0},
{}
};
MODULE_DEVICE_TABLE(i2c, st_nci_i2c_id_table);
static const struct acpi_device_id st_nci_i2c_acpi_match[] = {
{"SMO2101"},
{"SMO2102"},
{}
};
MODULE_DEVICE_TABLE(acpi, st_nci_i2c_acpi_match);
static const struct of_device_id of_st_nci_i2c_match[] = {
{ .compatible = "st,st21nfcb-i2c", },
{ .compatible = "st,st21nfcb_i2c", },
{ .compatible = "st,st21nfcc-i2c", },
{}
};
MODULE_DEVICE_TABLE(of, of_st_nci_i2c_match);
static struct i2c_driver st_nci_i2c_driver = {
.driver = {
.name = ST_NCI_I2C_DRIVER_NAME,
.of_match_table = of_match_ptr(of_st_nci_i2c_match),
.acpi_match_table = ACPI_PTR(st_nci_i2c_acpi_match),
},
.probe = st_nci_i2c_probe,
.id_table = st_nci_i2c_id_table,
.remove = st_nci_i2c_remove,
};
module_i2c_driver(st_nci_i2c_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(DRIVER_DESC);