On Thu, Jun 28, 2018 at 9:10 PM, Manivannan Sadhasivam
[off-list ref] wrote:

Add Actions Semi OWL family S900 I2C driver.

+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of_device.h>

+#include <linux/io.h>

Perhaps keep in order?

+#define OWL_I2C_DEFAULT_SPEED  100000
+#define OWL_I2C_MAX_SPEED      400000

..._SPEED -> ..._SPEED_HZ ?

DEFAULT -> DEF ?

+static int owl_i2c_reset(struct owl_i2c_dev *i2c_dev)
+{
+       unsigned int val, timeout = 0;
+
+       owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
+                               OWL_I2C_CTL_EN, false);

+       mdelay(1);

1 ms keeping CPU busy for nothing. Perhaps usleep_range() / msleep()?
Is it called in atomic context?

+       owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
+                               OWL_I2C_CTL_EN, true);
+
+       /* Reset FIFO */
+       owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
+                               OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR,
+                               true);
+
+       /* Wait 50ms for FIFO reset complete */
+       do {
+               val = readl(i2c_dev->base + OWL_I2C_REG_FIFOCTL);
+               if (!(val & (OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR)))
+                       break;

+               mdelay(1);

Ditto.

+       } while (timeout++ < OWL_I2C_MAX_RETRIES);

OK, I see you call it from IRQ context. 50ms for IRQ handler is
inappropriate. (1ms either, but@least not so drastically).

+}

+static irqreturn_t owl_i2c_interrupt(int irq, void *_dev)
+{

+       stat = readl(i2c_dev->base + OWL_I2C_REG_STAT);
+       if (stat & OWL_I2C_STAT_BEB) {
+               dev_dbg(&i2c_dev->adap.dev, "bus error");

+               owl_i2c_reset(i2c_dev);

This is questionable to be here (looking at so loong delays in it).

+               goto stop;
+       }

+       return IRQ_HANDLED;
+}

+static int owl_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+                               int num)
+{

+       int ret = 0, idx;

Redundant assignment.

+       ret = owl_i2c_hw_init(i2c_dev);
+       if (ret)
+               return ret;

+}

+static const struct i2c_algorithm owl_i2c_algorithm = {
+       .master_xfer    = owl_i2c_master_xfer,

+       .functionality  = owl_i2c_func

Slightly better to keep comma at the end

+};
+
+static const struct i2c_adapter_quirks owl_i2c_quirks = {
+       .flags          = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST,
+       .max_read_len   = 240,
+       .max_write_len  = 240,
+       .max_comb_1st_msg_len = 6,
+       .max_comb_2nd_msg_len = 240

Ditto.

+};

-- 
With Best Regards,
Andy Shevchenko