| // 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) |
| { |
| 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 }, |
| { } |
| }; |
| 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); |