Hi Morimoto-san,
Apologies for the late review, I have some comments below.
Thanks,
Phil
<snip>
> +static void rcar_i2c_write(struct rcar_i2c_priv *priv, int reg, u32
val)
> +{
> + __raw_writel(val, priv->io + reg);
> +}
> +
> +static u32 rcar_i2c_read(struct rcar_i2c_priv *priv, int reg)
> +{
> + return __raw_readl(priv->io + reg);
> +}
I think we should use writel/readl here. We have a number of devices where
the virtual address map conflicts with register addresses for other
peripherals.
<snip>
> +static void rcar_i2c_bus_phase(struct rcar_i2c_priv *priv, int phase)
> +{
> + switch (phase) {
> + case RCAR_BUS_PHASE_ADDR:
> + rcar_i2c_write(priv, ICMCR, MDBS | MIE | ESG);
> + break;
> + case RCAR_BUS_PHASE_DATA:
> + rcar_i2c_write(priv, ICMCR, MDBS | MIE);
> + break;
> + case RCAR_BUS_PHASE_STOP:
> + rcar_i2c_write(priv, ICMCR, MDBS | MIE | FSB);
> + break;
> + }
> +
> + return;
> +}
Don't need the return.
> +
> +/*
> + * clock function
> + */
> +static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv,
> + u32 bus_speed,
> + struct device *dev)
> +{
> + struct clk *clkp = clk_get(NULL, "peripheral_clk");
> + u32 scgd, cdf;
> + u32 round, ick;
> +
> + if (!clkp) {
> + dev_err(dev, "there is no peripheral_clk\n");
> + return -EIO;
> + }
> +
> + /*
> + * use 95% bus speed for safety.
> + */
> + bus_speed = bus_speed * 95 / 100;
Why do you use 95% of the bus speed? Surely, either the hardware supports
a specific speed or it doesn't.
> +
> + /*
> + * calculate SCL clock
> + * see
> + * ICCCR
> + *
> + * ick = clkp / (1 + CDF)
> + * SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
> + *
> + * ick : I2C internal clock < 20 MHz
> + * ticf : I2C SCL falling time = 35 ns here
> + * tr : I2C SCL rising time = 200 ns here
> + * intd : LSI internal delay = 50 ns here
> + * clkp : peripheral_clk
> + * F[] : integer up-valuation
> + */
> + for (cdf = 0; cdf < 4; cdf++) {
> + ick = clk_get_rate(clkp) / (1 + cdf);
> + if (ick < 20000000)
> + goto ick_find;
> + }
> + dev_err(dev, "there is no best CDF\n");
> +
> + return -EIO;
> +
> +ick_find:
> + /*
> + * it is impossible to calculate large scale
> + * number on u32
> + *
> + * F[(ticf + tr + intd) * ick]
> + * = F[(35 + 200 + 50)ns * ick]
> + * = F[285 * ick / 1000000000]
> + * = F[(ick / 1000000) * 285 / 1000]
> + */
> + round = (ick + 500000) / 1000000 * 285;
> + round = (round + 500) / 1000;
Now that I see this, I guess that you used 95% bus clock due to rounding
errors here. If so, maybe it would be better to try to improve this
calculation.
<snip>
> +static int rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
> +{
> + struct i2c_msg *msg = priv->msg;
> +
> + /*
> + * FIXME
> + * sometimes, unknown interrupt happend.
typo: happend => happened
> + * Do nothing
> + */
> + if (!(msr & MDE))
> + return 0;
> +
> + /*
> + * If address transfer phase finised,
typo: finised => finished
<snip>
> +static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr)
> +{
> + struct i2c_msg *msg = priv->msg;
> +
> + /*
> + * FIXME
> + * sometimes, unknown interrupt happend.
typo: happend => happened
<snip>
> +static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
> + struct i2c_msg *msgs,
> + int num)
> +{
> + struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
> + struct device *dev = rcar_i2c_priv_to_dev(priv);
> + unsigned long flags;
> + int i, ret, timeout;
> +
> + /*================== enable i2c device ===================*/
> + pm_runtime_get_sync(dev);
> +
> + /*-------------- spin lock -----------------*/
> + spin_lock_irqsave(&priv->lock, flags);
> +
> + rcar_i2c_soft_reset(priv);
> + rcar_i2c_clock_start(priv);
> +
> + spin_unlock_irqrestore(&priv->lock, flags);
> + /*-------------- spin unlock -----------------*/
> +
> + ret = -EINVAL;
> + for (i = 0; i < num; i++) {
> + /*-------------- spin lock -----------------*/
> + spin_lock_irqsave(&priv->lock, flags);
> +
> + /* init each data */
> + priv->msg = &msgs[i];
> + priv->pos = 0;
> + priv->flags = 0;
> + if (priv->msg == &msgs[num - 1])
> + rcar_i2c_flags_set(priv, ID_LAST_MSG);
> +
> + /* start send/recv */
> + if (rcar_i2c_is_recv(priv))
> + ret = rcar_i2c_recv(priv);
> + else
> + ret = rcar_i2c_send(priv);
> +
> + spin_unlock_irqrestore(&priv->lock, flags);
> + /*-------------- spin unlock -----------------*/
> +
> + if (ret < 0)
> + break;
> +
> + /*
> + * wait result
> + */
> + timeout = wait_event_timeout(priv->wait,
> + rcar_i2c_flags_has(priv, ID_DONE),
> + 5 * HZ);
> + if (!timeout) {
> + ret = -ETIMEDOUT;
> + break;
> + }
> +
> + /*
> + * error handling
> + */
> + if (rcar_i2c_flags_has(priv, ID_NACK)) {
> + ret = -EREMOTEIO;
> +
> + if (msgs->flags & I2C_M_IGNORE_NAK)
> + ret = 0;
> + break;
> + }
> +
> + if (rcar_i2c_flags_has(priv, ID_ARBLOST)) {
> + ret = -EAGAIN;
> + break;
> + }
> +
> + if (rcar_i2c_flags_has(priv, ID_IOERROR)) {
> + ret = -EIO;
> + break;
> + }
> +
> + ret = i + 1; /* The number of transfer */
> + }
> +
> + pm_runtime_put_sync(dev);
> + /*================== disable i2c device ===================*/
This comment should be above the previous line, unless you the comment is
meant to say "i2c device disabled"
> +
> + if (ret < 0)
> + dev_err(dev, "error %d : %x\n", ret, priv->flags);
> +
> + return ret;
> +}
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