diff options
Diffstat (limited to 'drivers/nfc/st21nfca/i2c.c')
| -rw-r--r-- | drivers/nfc/st21nfca/i2c.c | 624 |
1 files changed, 624 insertions, 0 deletions
diff --git a/drivers/nfc/st21nfca/i2c.c b/drivers/nfc/st21nfca/i2c.c new file mode 100644 index 0000000..cd1f7bf --- /dev/null +++ b/drivers/nfc/st21nfca/i2c.c @@ -0,0 +1,624 @@ +/* + * 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; +} + +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) { + 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; +} + +/* + * 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; + 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; +} + +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); +} + +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; +} + +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); |