/* * 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.h> #include <linux/of_irq.h> #include <linux/of_gpio.h> #include <linux/miscdevice.h> #include <linux/interrupt.h> #include <linux/delay.h> #include <linux/nfc.h> #include <linux/firmware.h> #include <linux/unaligned/access_ok.h> #include <linux/platform_data/st21nfca.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_I2C_DRIVER_NAME "st21nfca_hci_i2c" static struct i2c_device_id st21nfca_hci_i2c_id_table[] = { {ST21NFCA_HCI_DRIVER_NAME, 0}, {} }; MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table); struct st21nfca_i2c_phy { struct i2c_client *i2c_dev; struct nfc_hci_dev *hdev; unsigned int gpio_ena; unsigned int gpio_irq; unsigned int irq_polarity; 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; gpio_set_value(phy->gpio_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; pr_info("\n"); gpio_set_value(phy->gpio_ena, 0); phy->powered = 0; } static void st21nfca_hci_add_len_crc(struct sk_buff *skb) { u16 crc; u8 tmp; *skb_push(skb, 1) = 0; crc = crc_ccitt(0xffff, skb->data, skb->len); crc = ~crc; tmp = crc & 0x00ff; *skb_put(skb, 1) = tmp; tmp = (crc >> 8) & 0x00ff; *skb_put(skb, 1) = 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(skb, 1) = ST21NFCA_SOF_EOF; /* add ST21NFCA_SOF_EOF on head */ *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; } memcpy(skb_put(skb, len), 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, }; #ifdef CONFIG_OF static int st21nfca_hci_i2c_of_request_resources(struct i2c_client *client) { struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client); struct device_node *pp; int gpio; int r; pp = client->dev.of_node; if (!pp) return -ENODEV; /* Get GPIO from device tree */ gpio = of_get_named_gpio(pp, "enable-gpios", 0); if (gpio < 0) { nfc_err(&client->dev, "Failed to retrieve enable-gpios from device tree\n"); return gpio; } /* GPIO request and configuration */ r = devm_gpio_request_one(&client->dev, gpio, GPIOF_OUT_INIT_HIGH, "clf_enable"); if (r) { nfc_err(&client->dev, "Failed to request enable pin\n"); return -ENODEV; } phy->gpio_ena = gpio; /* IRQ */ r = irq_of_parse_and_map(pp, 0); if (r < 0) { nfc_err(&client->dev, "Unable to get irq, error: %d\n", r); return r; } phy->irq_polarity = irq_get_trigger_type(r); client->irq = r; return 0; } #else static int st21nfca_hci_i2c_of_request_resources(struct i2c_client *client) { return -ENODEV; } #endif static int st21nfca_hci_i2c_request_resources(struct i2c_client *client) { struct st21nfca_nfc_platform_data *pdata; struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client); int r; int irq; pdata = client->dev.platform_data; if (pdata == NULL) { nfc_err(&client->dev, "No platform data\n"); return -EINVAL; } /* store for later use */ phy->gpio_irq = pdata->gpio_irq; phy->gpio_ena = pdata->gpio_ena; phy->irq_polarity = pdata->irq_polarity; r = devm_gpio_request_one(&client->dev, phy->gpio_irq, GPIOF_IN, "wake_up"); if (r) { pr_err("%s : gpio_request failed\n", __FILE__); return -ENODEV; } if (phy->gpio_ena > 0) { r = devm_gpio_request_one(&client->dev, phy->gpio_ena, GPIOF_OUT_INIT_HIGH, "clf_enable"); if (r) { pr_err("%s : ena gpio_request failed\n", __FILE__); return -ENODEV; } } /* IRQ */ irq = gpio_to_irq(phy->gpio_irq); if (irq < 0) { nfc_err(&client->dev, "Unable to get irq number for GPIO %d error %d\n", phy->gpio_irq, r); return -ENODEV; } client->irq = irq; return 0; } static int st21nfca_hci_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct st21nfca_i2c_phy *phy; struct st21nfca_nfc_platform_data *pdata; 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) { nfc_err(&client->dev, "Cannot allocate memory for st21nfca i2c phy.\n"); 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); pdata = client->dev.platform_data; if (!pdata && client->dev.of_node) { r = st21nfca_hci_i2c_of_request_resources(client); if (r) { nfc_err(&client->dev, "No platform data\n"); return r; } } else if (pdata) { r = st21nfca_hci_i2c_request_resources(client); if (r) { nfc_err(&client->dev, "Cannot get platform resources\n"); return r; } } else { nfc_err(&client->dev, "st21nfca platform resources not available\n"); return -ENODEV; } r = st21nfca_hci_platform_init(phy); if (r < 0) { nfc_err(&client->dev, "Unable to reboot st21nfca\n"); return -ENODEV; } r = devm_request_threaded_irq(&client->dev, client->irq, NULL, st21nfca_hci_irq_thread_fn, phy->irq_polarity | 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); } 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 const struct of_device_id of_st21nfca_i2c_match[] = { { .compatible = "st,st21nfca_i2c", }, {} }; static struct i2c_driver st21nfca_hci_i2c_driver = { .driver = { .owner = THIS_MODULE, .name = ST21NFCA_HCI_I2C_DRIVER_NAME, .of_match_table = of_match_ptr(of_st21nfca_i2c_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);