diff options
Diffstat (limited to 'drivers/nfc/microread/i2c.c')
| -rw-r--r-- | drivers/nfc/microread/i2c.c | 298 |
1 files changed, 298 insertions, 0 deletions
diff --git a/drivers/nfc/microread/i2c.c b/drivers/nfc/microread/i2c.c new file mode 100644 index 000000000..5eaa18f81 --- /dev/null +++ b/drivers/nfc/microread/i2c.c @@ -0,0 +1,298 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * HCI based Driver for Inside Secure microread NFC Chip - i2c layer + * + * Copyright (C) 2013 Intel Corporation. All rights reserved. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/i2c.h> +#include <linux/delay.h> +#include <linux/slab.h> +#include <linux/interrupt.h> +#include <linux/gpio.h> + +#include <linux/nfc.h> +#include <net/nfc/hci.h> +#include <net/nfc/llc.h> + +#include "microread.h" + +#define MICROREAD_I2C_DRIVER_NAME "microread" + +#define MICROREAD_I2C_FRAME_HEADROOM 1 +#define MICROREAD_I2C_FRAME_TAILROOM 1 + +/* framing in HCI mode */ +#define MICROREAD_I2C_LLC_LEN 1 +#define MICROREAD_I2C_LLC_CRC 1 +#define MICROREAD_I2C_LLC_LEN_CRC (MICROREAD_I2C_LLC_LEN + \ + MICROREAD_I2C_LLC_CRC) +#define MICROREAD_I2C_LLC_MIN_SIZE (1 + MICROREAD_I2C_LLC_LEN_CRC) +#define MICROREAD_I2C_LLC_MAX_PAYLOAD 29 +#define MICROREAD_I2C_LLC_MAX_SIZE (MICROREAD_I2C_LLC_LEN_CRC + 1 + \ + MICROREAD_I2C_LLC_MAX_PAYLOAD) + +struct microread_i2c_phy { + struct i2c_client *i2c_dev; + struct nfc_hci_dev *hdev; + + 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 microread_i2c_add_len_crc(struct sk_buff *skb) +{ + int i; + u8 crc = 0; + int len; + + len = skb->len; + *(u8 *)skb_push(skb, 1) = len; + + for (i = 0; i < skb->len; i++) + crc = crc ^ skb->data[i]; + + skb_put_u8(skb, crc); +} + +static void microread_i2c_remove_len_crc(struct sk_buff *skb) +{ + skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM); + skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM); +} + +static int check_crc(const struct sk_buff *skb) +{ + int i; + u8 crc = 0; + + for (i = 0; i < skb->len - 1; i++) + crc = crc ^ skb->data[i]; + + if (crc != skb->data[skb->len-1]) { + pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]); + pr_info("%s: BAD CRC\n", __func__); + return -EPERM; + } + + return 0; +} + +static int microread_i2c_enable(void *phy_id) +{ + return 0; +} + +static void microread_i2c_disable(void *phy_id) +{ + return; +} + +static int microread_i2c_write(void *phy_id, struct sk_buff *skb) +{ + int r; + struct microread_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); + + microread_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; + } + + microread_i2c_remove_len_crc(skb); + + return r; +} + + +static int microread_i2c_read(struct microread_i2c_phy *phy, + struct sk_buff **skb) +{ + int r; + u8 len; + u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1]; + struct i2c_client *client = phy->i2c_dev; + + r = i2c_master_recv(client, &len, 1); + if (r != 1) { + nfc_err(&client->dev, "cannot read len byte\n"); + return -EREMOTEIO; + } + + if ((len < MICROREAD_I2C_LLC_MIN_SIZE) || + (len > MICROREAD_I2C_LLC_MAX_SIZE)) { + nfc_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_u8(*skb, len); + + r = i2c_master_recv(client, skb_put(*skb, len), len); + if (r != len) { + kfree_skb(*skb); + return -EREMOTEIO; + } + + I2C_DUMP_SKB("cc frame read", *skb); + + r = check_crc(*skb); + if (r != 0) { + kfree_skb(*skb); + r = -EBADMSG; + goto flush; + } + + skb_pull(*skb, 1); + skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM); + + usleep_range(3000, 6000); + + return 0; + +flush: + if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0) + r = -EREMOTEIO; + + usleep_range(3000, 6000); + + return r; +} + +static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id) +{ + struct microread_i2c_phy *phy = phy_id; + struct sk_buff *skb = NULL; + int r; + + if (!phy || irq != phy->i2c_dev->irq) { + WARN_ON_ONCE(1); + return IRQ_NONE; + } + + if (phy->hard_fault != 0) + return IRQ_HANDLED; + + r = microread_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 const struct nfc_phy_ops i2c_phy_ops = { + .write = microread_i2c_write, + .enable = microread_i2c_enable, + .disable = microread_i2c_disable, +}; + +static int microread_i2c_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct microread_i2c_phy *phy; + int r; + + phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy), + GFP_KERNEL); + if (!phy) + return -ENOMEM; + + i2c_set_clientdata(client, phy); + phy->i2c_dev = client; + + r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn, + IRQF_TRIGGER_RISING | IRQF_ONESHOT, + MICROREAD_I2C_DRIVER_NAME, phy); + if (r) { + nfc_err(&client->dev, "Unable to register IRQ handler\n"); + return r; + } + + r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME, + MICROREAD_I2C_FRAME_HEADROOM, + MICROREAD_I2C_FRAME_TAILROOM, + MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev); + if (r < 0) + goto err_irq; + + return 0; + +err_irq: + free_irq(client->irq, phy); + + return r; +} + +static void microread_i2c_remove(struct i2c_client *client) +{ + struct microread_i2c_phy *phy = i2c_get_clientdata(client); + + microread_remove(phy->hdev); + + free_irq(client->irq, phy); +} + +static const struct i2c_device_id microread_i2c_id[] = { + { MICROREAD_I2C_DRIVER_NAME, 0}, + { } +}; +MODULE_DEVICE_TABLE(i2c, microread_i2c_id); + +static struct i2c_driver microread_i2c_driver = { + .driver = { + .name = MICROREAD_I2C_DRIVER_NAME, + }, + .probe = microread_i2c_probe, + .remove = microread_i2c_remove, + .id_table = microread_i2c_id, +}; + +module_i2c_driver(microread_i2c_driver); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION(DRIVER_DESC); |