cregit-Linux how code gets into the kernel

Release 4.14 drivers/nfc/st21nfca/i2c.c

/*
 * I2C Link Layer for ST21NFCA HCI based Driver
 * Copyright (C) 2014  STMicroelectronics SAS. 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, see <http://www.gnu.org/licenses/>.
 */


#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 <asm/unaligned.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 u8 len_seq[] = { 16, 24, 12, 29 };

static 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; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard224100.00%3100.00%
Total224100.00%3100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard4695.83%150.00%
Andy Shevchenko24.17%150.00%
Total48100.00%2100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard3093.75%150.00%
Andy Shevchenko26.25%150.00%
Total32100.00%2100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard7390.12%250.00%
Johannes Berg89.88%250.00%
Total81100.00%4100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard29100.00%2100.00%
Total29100.00%2100.00%

/* * 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; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard30398.06%250.00%
Johannes Berg61.94%250.00%
Total309100.00%4100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard56100.00%1100.00%
Total56100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard120100.00%1100.00%
Total120100.00%1100.00%

/* * 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) { i = 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; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard234100.00%2100.00%
Total234100.00%2100.00%

/* * 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; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard25899.61%480.00%
Johannes Berg10.39%120.00%
Total259100.00%5100.00%

/* * 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; struct i2c_client *client; 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 = 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; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard261100.00%3100.00%
Total261100.00%3100.00%

static 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, const struct i2c_device_id *id) { struct device *dev = &client->dev; struct st21nfca_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(&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"); return PTR_ERR(phy->gpiod_ena); } 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"); return r; } 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"); return r; } return 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); }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard29580.60%975.00%
Andy Shevchenko7119.40%325.00%
Total366100.00%12100.00%


static int st21nfca_hci_i2c_remove(struct i2c_client *client) { struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client); dev_dbg(&client->dev, "%s\n", __func__); st21nfca_hci_remove(phy->hdev); if (phy->powered) st21nfca_hci_i2c_disable(phy); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard54100.00%1100.00%
Total54100.00%1100.00%

static struct i2c_device_id st21nfca_hci_i2c_id_table[] = { {ST21NFCA_HCI_DRIVER_NAME, 0}, {} }; MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table); static const struct acpi_device_id st21nfca_hci_i2c_acpi_match[] = { {"SMO2100", 0}, {} }; MODULE_DEVICE_TABLE(acpi, st21nfca_hci_i2c_acpi_match); static const struct of_device_id of_st21nfca_i2c_match[] = { { .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);

Overall Contributors

PersonTokensPropCommitsCommitProp
Christophe Ricard233194.60%2068.97%
Andy Shevchenko1174.75%517.24%
Johannes Berg160.65%413.79%
Total2464100.00%29100.00%
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with cregit.