diff options
Diffstat (limited to 'drivers/nfc/pn544/i2c.c')
| -rw-r--r-- | drivers/nfc/pn544/i2c.c | 500 |
1 files changed, 500 insertions, 0 deletions
diff --git a/drivers/nfc/pn544/i2c.c b/drivers/nfc/pn544/i2c.c new file mode 100644 index 000000000000..7da9071b68b6 --- /dev/null +++ b/drivers/nfc/pn544/i2c.c @@ -0,0 +1,500 @@ +/* + * I2C Link Layer for PN544 HCI based Driver + * + * Copyright (C) 2012 Intel Corporation. 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, write to the + * Free Software Foundation, Inc., + * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + */ + +#include <linux/crc-ccitt.h> +#include <linux/module.h> +#include <linux/i2c.h> +#include <linux/gpio.h> +#include <linux/miscdevice.h> +#include <linux/interrupt.h> +#include <linux/delay.h> + +#include <linux/platform_data/pn544.h> + +#include <net/nfc/hci.h> +#include <net/nfc/llc.h> + +#include "pn544.h" + +#define PN544_I2C_FRAME_HEADROOM 1 +#define PN544_I2C_FRAME_TAILROOM 2 + +/* framing in HCI mode */ +#define PN544_HCI_I2C_LLC_LEN 1 +#define PN544_HCI_I2C_LLC_CRC 2 +#define PN544_HCI_I2C_LLC_LEN_CRC (PN544_HCI_I2C_LLC_LEN + \ + PN544_HCI_I2C_LLC_CRC) +#define PN544_HCI_I2C_LLC_MIN_SIZE (1 + PN544_HCI_I2C_LLC_LEN_CRC) +#define PN544_HCI_I2C_LLC_MAX_PAYLOAD 29 +#define PN544_HCI_I2C_LLC_MAX_SIZE (PN544_HCI_I2C_LLC_LEN_CRC + 1 + \ + PN544_HCI_I2C_LLC_MAX_PAYLOAD) + +static struct i2c_device_id pn544_hci_i2c_id_table[] = { + {"pn544", 0}, + {} +}; + +MODULE_DEVICE_TABLE(i2c, pn544_hci_i2c_id_table); + +#define PN544_HCI_I2C_DRIVER_NAME "pn544_hci_i2c" + +struct pn544_i2c_phy { + struct i2c_client *i2c_dev; + struct nfc_hci_dev *hdev; + + unsigned int gpio_en; + unsigned int gpio_irq; + unsigned int gpio_fw; + unsigned int en_polarity; + + int powered; + + int hard_fault; /* + * < 0 if hardware error occured (e.g. i2c err) + * and prevents normal operation. + */ +}; + +#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) + +static void pn544_hci_i2c_platform_init(struct pn544_i2c_phy *phy) +{ + int polarity, retry, ret; + char rset_cmd[] = { 0x05, 0xF9, 0x04, 0x00, 0xC3, 0xE5 }; + int count = sizeof(rset_cmd); + + pr_info(DRIVER_DESC ": %s\n", __func__); + dev_info(&phy->i2c_dev->dev, "Detecting nfc_en polarity\n"); + + /* Disable fw download */ + gpio_set_value(phy->gpio_fw, 0); + + for (polarity = 0; polarity < 2; polarity++) { + phy->en_polarity = polarity; + retry = 3; + while (retry--) { + /* power off */ + gpio_set_value(phy->gpio_en, !phy->en_polarity); + usleep_range(10000, 15000); + + /* power on */ + gpio_set_value(phy->gpio_en, phy->en_polarity); + usleep_range(10000, 15000); + + /* send reset */ + dev_dbg(&phy->i2c_dev->dev, "Sending reset cmd\n"); + ret = i2c_master_send(phy->i2c_dev, rset_cmd, count); + if (ret == count) { + dev_info(&phy->i2c_dev->dev, + "nfc_en polarity : active %s\n", + (polarity == 0 ? "low" : "high")); + goto out; + } + } + } + + dev_err(&phy->i2c_dev->dev, + "Could not detect nfc_en polarity, fallback to active high\n"); + +out: + gpio_set_value(phy->gpio_en, !phy->en_polarity); +} + +static int pn544_hci_i2c_enable(void *phy_id) +{ + struct pn544_i2c_phy *phy = phy_id; + + pr_info(DRIVER_DESC ": %s\n", __func__); + + gpio_set_value(phy->gpio_fw, 0); + gpio_set_value(phy->gpio_en, phy->en_polarity); + usleep_range(10000, 15000); + + phy->powered = 1; + + return 0; +} + +static void pn544_hci_i2c_disable(void *phy_id) +{ + struct pn544_i2c_phy *phy = phy_id; + + pr_info(DRIVER_DESC ": %s\n", __func__); + + gpio_set_value(phy->gpio_fw, 0); + gpio_set_value(phy->gpio_en, !phy->en_polarity); + usleep_range(10000, 15000); + + gpio_set_value(phy->gpio_en, phy->en_polarity); + usleep_range(10000, 15000); + + gpio_set_value(phy->gpio_en, !phy->en_polarity); + usleep_range(10000, 15000); + + phy->powered = 0; +} + +static void pn544_hci_i2c_add_len_crc(struct sk_buff *skb) +{ + u16 crc; + int len; + + len = skb->len + 2; + *skb_push(skb, 1) = len; + + crc = crc_ccitt(0xffff, skb->data, skb->len); + crc = ~crc; + *skb_put(skb, 1) = crc & 0xff; + *skb_put(skb, 1) = crc >> 8; +} + +static void pn544_hci_i2c_remove_len_crc(struct sk_buff *skb) +{ + skb_pull(skb, PN544_I2C_FRAME_HEADROOM); + skb_trim(skb, PN544_I2C_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 pn544_hci_i2c_write(void *phy_id, struct sk_buff *skb) +{ + int r; + struct pn544_i2c_phy *phy = phy_id; + struct i2c_client *client = phy->i2c_dev; + + if (phy->hard_fault != 0) + return phy->hard_fault; + + usleep_range(3000, 6000); + + pn544_hci_i2c_add_len_crc(skb); + + I2C_DUMP_SKB("i2c frame written", skb); + + r = i2c_master_send(client, skb->data, skb->len); + + if (r == -EREMOTEIO) { /* Retry, chip was in standby */ + usleep_range(6000, 10000); + r = i2c_master_send(client, skb->data, skb->len); + } + + if (r >= 0) { + if (r != skb->len) + r = -EREMOTEIO; + else + r = 0; + } + + pn544_hci_i2c_remove_len_crc(skb); + + return r; +} + +static int check_crc(u8 *buf, int buflen) +{ + int len; + u16 crc; + + len = buf[0] + 1; + crc = crc_ccitt(0xffff, buf, len - 2); + crc = ~crc; + + if (buf[len - 2] != (crc & 0xff) || buf[len - 1] != (crc >> 8)) { + pr_err(PN544_HCI_I2C_DRIVER_NAME + ": CRC error 0x%x != 0x%x 0x%x\n", + crc, buf[len - 1], buf[len - 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; +} + +/* + * 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: + * -EREMOTEIO : i2c read error (fatal) + * -EBADMSG : frame was incorrect and discarded + * -ENOMEM : cannot allocate skb, frame dropped + */ +static int pn544_hci_i2c_read(struct pn544_i2c_phy *phy, struct sk_buff **skb) +{ + int r; + u8 len; + u8 tmp[PN544_HCI_I2C_LLC_MAX_SIZE - 1]; + struct i2c_client *client = phy->i2c_dev; + + r = i2c_master_recv(client, &len, 1); + if (r != 1) { + dev_err(&client->dev, "cannot read len byte\n"); + return -EREMOTEIO; + } + + if ((len < (PN544_HCI_I2C_LLC_MIN_SIZE - 1)) || + (len > (PN544_HCI_I2C_LLC_MAX_SIZE - 1))) { + dev_err(&client->dev, "invalid len byte\n"); + r = -EBADMSG; + goto flush; + } + + *skb = alloc_skb(1 + len, GFP_KERNEL); + if (*skb == NULL) { + r = -ENOMEM; + goto flush; + } + + *skb_put(*skb, 1) = len; + + r = i2c_master_recv(client, skb_put(*skb, len), len); + if (r != len) { + kfree_skb(*skb); + return -EREMOTEIO; + } + + I2C_DUMP_SKB("i2c frame read", *skb); + + r = check_crc((*skb)->data, (*skb)->len); + if (r != 0) { + kfree_skb(*skb); + r = -EBADMSG; + goto flush; + } + + skb_pull(*skb, 1); + skb_trim(*skb, (*skb)->len - 2); + + usleep_range(3000, 6000); + + return 0; + +flush: + if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0) + r = -EREMOTEIO; + + usleep_range(3000, 6000); + + return r; +} + +/* + * Reads an shdlc frame from the chip. This is not as straightforward as it + * seems. There are cases where we could loose the frame start synchronization. + * The frame format is len-data-crc, and corruption can occur anywhere while + * transiting on i2c bus, such that we could read an invalid len. + * In order to recover synchronization with the next frame, we must be sure + * to read the real amount of data without using the len byte. We do this by + * assuming the following: + * - the chip will always present only one single complete frame on the bus + * before triggering the interrupt + * - the chip will not present a new frame until we have completely read + * the previous one (or until we have handled the interrupt). + * The tricky case is when we read a corrupted len that is less than the real + * len. We must detect this here in order to determine that we need to flush + * the bus. This is the reason why we check the crc here. + */ +static irqreturn_t pn544_hci_i2c_irq_thread_fn(int irq, void *phy_id) +{ + struct pn544_i2c_phy *phy = phy_id; + struct i2c_client *client; + struct sk_buff *skb = NULL; + 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 = pn544_hci_i2c_read(phy, &skb); + if (r == -EREMOTEIO) { + phy->hard_fault = r; + + nfc_hci_recv_frame(phy->hdev, NULL); + + return IRQ_HANDLED; + } else if ((r == -ENOMEM) || (r == -EBADMSG)) { + return IRQ_HANDLED; + } + + nfc_hci_recv_frame(phy->hdev, skb); + + return IRQ_HANDLED; +} + +static struct nfc_phy_ops i2c_phy_ops = { + .write = pn544_hci_i2c_write, + .enable = pn544_hci_i2c_enable, + .disable = pn544_hci_i2c_disable, +}; + +static int __devinit pn544_hci_i2c_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct pn544_i2c_phy *phy; + struct pn544_nfc_platform_data *pdata; + int r = 0; + + 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)) { + dev_err(&client->dev, "Need I2C_FUNC_I2C\n"); + return -ENODEV; + } + + phy = kzalloc(sizeof(struct pn544_i2c_phy), GFP_KERNEL); + if (!phy) { + dev_err(&client->dev, + "Cannot allocate memory for pn544 i2c phy.\n"); + r = -ENOMEM; + goto err_phy_alloc; + } + + phy->i2c_dev = client; + i2c_set_clientdata(client, phy); + + pdata = client->dev.platform_data; + if (pdata == NULL) { + dev_err(&client->dev, "No platform data\n"); + r = -EINVAL; + goto err_pdata; + } + + if (pdata->request_resources == NULL) { + dev_err(&client->dev, "request_resources() missing\n"); + r = -EINVAL; + goto err_pdata; + } + + r = pdata->request_resources(client); + if (r) { + dev_err(&client->dev, "Cannot get platform resources\n"); + goto err_pdata; + } + + phy->gpio_en = pdata->get_gpio(NFC_GPIO_ENABLE); + phy->gpio_fw = pdata->get_gpio(NFC_GPIO_FW_RESET); + phy->gpio_irq = pdata->get_gpio(NFC_GPIO_IRQ); + + pn544_hci_i2c_platform_init(phy); + + r = request_threaded_irq(client->irq, NULL, pn544_hci_i2c_irq_thread_fn, + IRQF_TRIGGER_RISING | IRQF_ONESHOT, + PN544_HCI_I2C_DRIVER_NAME, phy); + if (r < 0) { + dev_err(&client->dev, "Unable to register IRQ handler\n"); + goto err_rti; + } + + r = pn544_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME, + PN544_I2C_FRAME_HEADROOM, PN544_I2C_FRAME_TAILROOM, + PN544_HCI_I2C_LLC_MAX_PAYLOAD, &phy->hdev); + if (r < 0) + goto err_hci; + + return 0; + +err_hci: + free_irq(client->irq, phy); + +err_rti: + if (pdata->free_resources != NULL) + pdata->free_resources(); + +err_pdata: + kfree(phy); + +err_phy_alloc: + return r; +} + +static __devexit int pn544_hci_i2c_remove(struct i2c_client *client) +{ + struct pn544_i2c_phy *phy = i2c_get_clientdata(client); + struct pn544_nfc_platform_data *pdata = client->dev.platform_data; + + dev_dbg(&client->dev, "%s\n", __func__); + + pn544_hci_remove(phy->hdev); + + if (phy->powered) + pn544_hci_i2c_disable(phy); + + free_irq(client->irq, phy); + if (pdata->free_resources) + pdata->free_resources(); + + kfree(phy); + + return 0; +} + +static struct i2c_driver pn544_hci_i2c_driver = { + .driver = { + .name = PN544_HCI_I2C_DRIVER_NAME, + }, + .probe = pn544_hci_i2c_probe, + .id_table = pn544_hci_i2c_id_table, + .remove = __devexit_p(pn544_hci_i2c_remove), +}; + +static int __init pn544_hci_i2c_init(void) +{ + int r; + + pr_debug(DRIVER_DESC ": %s\n", __func__); + + r = i2c_add_driver(&pn544_hci_i2c_driver); + if (r) { + pr_err(PN544_HCI_I2C_DRIVER_NAME + ": driver registration failed\n"); + return r; + } + + return 0; +} + +static void __exit pn544_hci_i2c_exit(void) +{ + i2c_del_driver(&pn544_hci_i2c_driver); +} + +module_init(pn544_hci_i2c_init); +module_exit(pn544_hci_i2c_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION(DRIVER_DESC); |