NFC: st21nfca: Synchronize i2c Tx and Rx path

Stabilize communication by using a mutex.
This avoids running a write transaction during a read retry or a read
transaction during a write retry.

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

diff --git a/drivers/nfc/st21nfca/i2c.c b/drivers/nfc/st21nfca/i2c.c
index 48f8e23fc3210b1f6166c214b9839d3fc801d2b0..b64d8e2e429a0ad3dd11840239d91c6dce69cb74 100644 (file)
--- a/drivers/nfc/st21nfca/i2c.c
+++ b/drivers/nfc/st21nfca/i2c.c
@@ -89,6 +89,7 @@ struct st21nfca_i2c_phy {
         * and prevents normal operation.
         */
        int hard_fault;
+       struct mutex phy_lock;
 };
 static u8 len_seq[] = { 13, 24, 15, 29 };
 static u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};
@@ -245,11 +246,13 @@ static int st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb)
         * 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)
@@ -375,11 +378,13 @@ static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy,
                 * 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;
@@ -575,6 +580,7 @@ static int st21nfca_hci_i2c_probe(struct i2c_client *client,
 
        phy->current_read_len = 0;
        phy->crc_trials = 0;
+       mutex_init(&phy->phy_lock);
        i2c_set_clientdata(client, phy);
 
        pdata = client->dev.platform_data;