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path: root/drivers/nfc/st21nfca/i2c.c
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Diffstat (limited to 'drivers/nfc/st21nfca/i2c.c')
-rw-r--r--drivers/nfc/st21nfca/i2c.c595
1 files changed, 595 insertions, 0 deletions
diff --git a/drivers/nfc/st21nfca/i2c.c b/drivers/nfc/st21nfca/i2c.c
new file mode 100644
index 000000000000..3b0fd0f76d1c
--- /dev/null
+++ b/drivers/nfc/st21nfca/i2c.c
@@ -0,0 +1,595 @@
+/*
+ * 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/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 fill size */
+#define ST21NFCA_FRAME_HEADROOM 2
+
+/* 4 bytes crc (worst case byte stuffing) + EOF */
+#define ST21NFCA_FRAME_TAILROOM 5
+
+#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;
+};
+static u8 len_seq[] = { 13, 24, 15, 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)
+
+static void st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy)
+{
+ u16 wait_tab[] = { 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_tab) && r < 0; i++)
+ r = i2c_master_recv(phy->i2c_dev, tmp,
+ ST21NFCA_HCI_LLC_MAX_SIZE);
+
+ r = -1;
+ for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++)
+ r = i2c_master_send(phy->i2c_dev, reboot_cmd,
+ sizeof(reboot_cmd));
+ usleep_range(1000, 1500);
+
+}
+
+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 int st21nfca_hci_add_len_crc(struct sk_buff *skb)
+{
+ int ret = 2;
+ 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;
+
+ return ret;
+}
+
+static void st21nfca_hci_remove_len_crc(struct sk_buff *skb, int crc_len)
+{
+ skb_pull(skb, ST21NFCA_FRAME_HEADROOM);
+ skb_trim(skb, crc_len);
+}
+
+/*
+ * 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, len;
+ struct st21nfca_i2c_phy *phy = phy_id;
+ struct i2c_client *client = phy->i2c_dev;
+ u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};
+ 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
+ */
+ len = 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
+ */
+ 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]);
+ }
+
+ if (r >= 0) {
+ if (r != j)
+ r = -EREMOTEIO;
+ else
+ r = 0;
+ }
+
+ st21nfca_hci_remove_len_crc(skb, len);
+
+ 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] ==
+ (u8) ST21NFCA_ESCAPE_BYTE_STUFFING) {
+ skb->data[i] =
+ skb->data[i +
+ 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;
+ 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;
+ for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) {
+ r = i2c_master_recv(client, skb_put(skb, len), len);
+ if (r < 0)
+ msleep(wait_tab[i]);
+ }
+
+ if (r != len) {
+ phy->current_read_len = 0;
+ return -EREMOTEIO;
+ }
+
+ if (memchr(skb->data + 2, ST21NFCA_SOF_EOF,
+ skb->len - 2) != NULL) {
+ 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;
+ } 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;
+ }
+
+ 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 int st21nfca_request_resources(struct st21nfca_i2c_phy *phy,
+ struct i2c_client *client)
+{
+ struct st21nfca_nfc_platform_data *pdata;
+ int r;
+
+ 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;
+ phy->i2c_dev = client;
+
+ r = devm_gpio_request(&client->dev, phy->gpio_irq, "wake_up");
+ if (r) {
+ pr_err("%s : gpio_request failed\n", __FILE__);
+ return -ENODEV;
+ }
+
+ r = gpio_direction_input(phy->gpio_irq);
+ if (r) {
+ pr_err("%s : gpio_direction_input failed\n", __FILE__);
+ return -ENODEV;
+ }
+
+ if (phy->gpio_ena != 0) {
+ r = devm_gpio_request(&client->dev,
+ phy->gpio_ena, "clf_enable");
+ if (r) {
+ pr_err("%s : ena gpio_request failed\n", __FILE__);
+ return -ENODEV;
+ }
+ r = gpio_direction_output(phy->gpio_ena, 1);
+
+ if (r) {
+ pr_err("%s : ena gpio_direction_output failed\n",
+ __FILE__);
+ return -ENODEV;
+ }
+ }
+
+ 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;
+ return r;
+}
+
+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 = 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)) {
+ 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;
+
+ i2c_set_clientdata(client, phy);
+
+ pdata = client->dev.platform_data;
+ if (pdata == NULL) {
+ nfc_err(&client->dev, "No platform data\n");
+ return -EINVAL;
+ }
+
+ r = st21nfca_request_resources(phy, client);
+ if (r) {
+ nfc_err(&client->dev, "Cannot get platform resources\n");
+ return r;
+ }
+
+ st21nfca_hci_platform_init(phy);
+ 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;
+ }
+
+ r = st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
+ ST21NFCA_FRAME_HEADROOM, ST21NFCA_FRAME_TAILROOM,
+ ST21NFCA_HCI_LLC_MAX_PAYLOAD, &phy->hdev);
+
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+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_driver st21nfca_hci_i2c_driver = {
+ .driver = {
+ .name = ST21NFCA_HCI_I2C_DRIVER_NAME,
+ },
+ .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);
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-22 20:54:10 +0300