i2c-cht-wc: Add locking to interrupt / smbus_xfer functions

Although unlikely without locking the smbux_xfer function may miss
the nack flag and further fixes in this patch-set add some more
complex constructions which need protection.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-cht-wc.c b/drivers/i2c/busses/i2c-cht-wc.c
index fe5caf7..09e0df4 100644 (file)
--- a/drivers/i2c/busses/i2c-cht-wc.c
+++ b/drivers/i2c/busses/i2c-cht-wc.c
@@ -47,6 +47,7 @@ struct cht_wc_i2c_adap {
        struct i2c_adapter adapter;
        wait_queue_head_t wait;
        struct irq_chip irqchip;
+       struct mutex adap_lock;
        struct mutex irqchip_lock;
        struct regmap *regmap;
        struct irq_domain *irq_domain;
@@ -63,10 +64,13 @@ static irqreturn_t cht_wc_i2c_adap_thread_handler(int id, void *data)
        struct cht_wc_i2c_adap *adap = data;
        int ret, reg;
 
+       mutex_lock(&adap->adap_lock);
+
        /* Read IRQs */
        ret = regmap_read(adap->regmap, CHT_WC_EXTCHGRIRQ, &reg);
        if (ret) {
                dev_err(&adap->adapter.dev, "Error reading extchgrirq reg\n");
+               mutex_unlock(&adap->adap_lock);
                return IRQ_NONE;
        }
 
@@ -80,6 +84,16 @@ static irqreturn_t cht_wc_i2c_adap_thread_handler(int id, void *data)
        if (ret)
                dev_err(&adap->adapter.dev, "Error writing extchgrirq reg\n");
 
+       if (reg & CHT_WC_EXTCHGRIRQ_ADAP_IRQMASK) {
+               adap->nack = !!(reg & CHT_WC_EXTCHGRIRQ_NACK_IRQ);
+               adap->done = true;
+       }
+
+       mutex_unlock(&adap->adap_lock);
+
+       if (reg & CHT_WC_EXTCHGRIRQ_ADAP_IRQMASK)
+               wake_up(&adap->wait);
+
        /*
         * Do NOT use handle_nested_irq here, the client irq handler will
         * likely want to do i2c transfers and the i2c controller uses this
@@ -96,12 +110,6 @@ static irqreturn_t cht_wc_i2c_adap_thread_handler(int id, void *data)
                local_irq_enable();
        }
 
-       if (reg & CHT_WC_EXTCHGRIRQ_ADAP_IRQMASK) {
-               adap->nack = !!(reg & CHT_WC_EXTCHGRIRQ_NACK_IRQ);
-               adap->done = true;
-               wake_up(&adap->wait);
-       }
-
        return IRQ_HANDLED;
 }
 
@@ -119,8 +127,10 @@ static int cht_wc_i2c_adap_smbus_xfer(struct i2c_adapter *_adap, u16 addr,
        struct cht_wc_i2c_adap *adap = i2c_get_adapdata(_adap);
        int ret, reg;
 
+       mutex_lock(&adap->adap_lock);
        adap->nack = false;
        adap->done = false;
+       mutex_unlock(&adap->adap_lock);
 
        ret = regmap_write(adap->regmap, CHT_WC_I2C_CLIENT_ADDR, addr);
        if (ret)
@@ -146,18 +156,18 @@ static int cht_wc_i2c_adap_smbus_xfer(struct i2c_adapter *_adap, u16 addr,
        ret = wait_event_timeout(adap->wait, adap->done, 3 * HZ);
        if (ret == 0)
                return -ETIMEDOUT;
-       if (adap->nack)
-               return -EIO;
 
-       if (read_write == I2C_SMBUS_READ) {
+       ret = 0;
+       mutex_lock(&adap->adap_lock);
+       if (adap->nack)
+               ret = -EIO;
+       else if (read_write == I2C_SMBUS_READ) {
                ret = regmap_read(adap->regmap, CHT_WC_I2C_RDDATA, &reg);
-               if (ret)
-                       return ret;
-
                data->byte = reg;
        }
+       mutex_unlock(&adap->adap_lock);
 
-       return 0;
+       return ret;
 }
 
 static const struct i2c_algorithm cht_wc_i2c_adap_algo = {
@@ -241,6 +251,7 @@ static int cht_wc_i2c_adap_i2c_probe(struct platform_device *pdev)
                return -ENOMEM;
 
        init_waitqueue_head(&adap->wait);
+       mutex_init(&adap->adap_lock);
        mutex_init(&adap->irqchip_lock);
        adap->irqchip = cht_wc_i2c_irq_chip;
        adap->regmap = pmic->regmap;