Re: [PATCH resend 2/2] i2c: hix5hd2: add i2c controller driver

[Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>]

Hi,

thanks for the submission.

> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-hix5hd2.c
> @@ -0,0 +1,573 @@
> +/*
> + * Copyright (c) 2014 Linaro Ltd.
> + * Copyright (c) 2014 Hisilicon Limited.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * publishhed by the Free Software Foundation.

"publishhed"

> + *
> + * Now only support 7 bit address.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>

I think there should be at least of.h, too.

> +struct hix5hd2_i2c {
> +	struct i2c_adapter adap;
> +	struct i2c_msg	*msg;
> +	unsigned int msg_ptr;	/* msg index */

Comment seems wrong. It looks to me as the msg buffer index. If so, the
variable name is also confusing.

> +	unsigned int len;	/* msg length */
> +	int stop;
> +	struct completion msg_complete;
> +
> +	unsigned int irq;

That can be a local variable.

> +	void __iomem *regs;
> +	struct clk *clk;
> +	struct device *dev;
> +	spinlock_t lock;	/* IRQ synchronization */
> +
> +	int err;
> +	enum hix5hd2_i2c_state state;
> +	enum hix5hd2_i2c_speed speed_mode;

Where is this needed?

> +
> +	/* Controller frequency */
> +	unsigned int s_clock;
> +};
> +
> +static void hix5hd2_i2c_drv_setrate(struct hix5hd2_i2c *i2c)
> +{
> +	u32 rate, val;
> +	u32 sclh, scll, sysclock;
> +
> +	/* close all i2c interrupt */
> +	val = readl_relaxed(i2c->regs + HIX5I2C_CTRL);
> +	writel_relaxed(val & (~I2C_UNMASK_TOTAL), i2c->regs + HIX5I2C_CTRL);
> +
> +	rate = i2c->s_clock;
> +	sysclock = clk_get_rate(i2c->clk);
> +	sclh = (sysclock / (rate * 2)) / 2 - 1;
> +	writel_relaxed(sclh, i2c->regs + HIX5I2C_SCL_H);
> +	scll = (sysclock / (rate * 2)) / 2 - 1;

scll and sclh use the same formula? Have you measured the setup
frequency with a scope?

> +	writel_relaxed(scll, i2c->regs + HIX5I2C_SCL_L);
> +
> +	/* restore original interrupt*/
> +	writel_relaxed(val, i2c->regs + HIX5I2C_CTRL);
> +
> +	dev_dbg(i2c->dev, "%s: sysclock=%d, rate=%d, sclh=%d, scll=%d\n",
> +		__func__, sysclock, rate, sclh, scll);
> +}
> +
> +static void hix5hd2_rw_over(struct hix5hd2_i2c *i2c)
> +{
> +	if (HIX5I2C_STAT_SND_STOP == i2c->state)

To be honest, I don't like having the constant on the left side. It
is far easier to read if they are on the right side. Plus, we have gcc
warnings to prevent the "=" and "==" mistake. Please switch them around
in this driver.

> +		dev_dbg(i2c->dev, "%s: rw and send stop over\n", __func__);
> +	else
> +		dev_dbg(i2c->dev, "%s: have not data to send\n", __func__);
> +
> +	i2c->state = HIX5I2C_STAT_RW_SUCCESS;
> +	i2c->err = 0;
> +}
> +

...

> +	/* handle error */
> +	if (int_status & I2C_ARBITRATE_INTR) {
> +		/*Bus error */

Space missing in front of "Bus". If this is an arbitration lost error,
then please use -EAGAIN. Check Documentation/i2c/fault-codes for the
convention.

> +		dev_dbg(i2c->dev, "ARB bus loss\n");
> +		i2c->err = -ENXIO;
> +		i2c->state = HIX5I2C_STAT_RW_ERR;
> +		goto stop;
> +	} else if (int_status & I2C_ACK_INTR) {
> +		/* ack error */
> +		dev_dbg(i2c->dev, "No ACK from device\n");
> +		i2c->err = -ENXIO;
> +		i2c->state = HIX5I2C_STAT_RW_ERR;
> +		goto stop;
> +	}
> +
> +static void hix5hd2_i2c_message_start(struct hix5hd2_i2c *i2c, int stop)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&i2c->lock, flags);
> +	hix5hd2_i2c_clr_all_irq(i2c);
> +	hix5hd2_i2c_enable_irq(i2c);
> +
> +	if (i2c->msg->flags & I2C_M_RD)
> +		writel_relaxed(i2c->msg->addr | HIX5I2C_READ_OPERATION,
> +			       i2c->regs + HIX5I2C_TXR);
> +	else
> +		writel_relaxed(i2c->msg->addr & HIX5I2C_WRITE_OPERATION,
> +			       i2c->regs + HIX5I2C_TXR);

??? Does this really work? i2c->msg->addr should be left shifted by 1?

> +
> +	writel_relaxed(I2C_WRITE | I2C_START, i2c->regs + HIX5I2C_COM);
> +	spin_unlock_irqrestore(&i2c->lock, flags);
> +}
> +
> +static int hix5hd2_i2c_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct hix5hd2_i2c *i2c;
> +	struct resource *mem;
> +	unsigned int op_clock;
> +	int ret;
> +
> +	i2c = devm_kzalloc(&pdev->dev, sizeof(struct hix5hd2_i2c), GFP_KERNEL);
> +	if (!i2c)
> +		return -ENOMEM;
> +
> +	if (of_property_read_u32(np, "clock-frequency", &op_clock)) {
> +		/* use default value */
> +		i2c->speed_mode = HIX5I2C_HIG_SPD;
> +		i2c->s_clock = HIX5I2C_HS_TX_CLOCK;

Please use 100kHz as the default. This is the speed devices should
support. 400kHz is optional. And I think 100000 is easier to read than a
define.

> +	} else {
> +		if (op_clock >= HIX5I2C_HS_TX_CLOCK) {
> +			i2c->speed_mode = HIX5I2C_HIG_SPD;
> +			i2c->s_clock = HIX5I2C_HS_TX_CLOCK;

So, if the speed is bigger than 400kHz, it will be capped down to
400kHz? Is that true? Then, the user should be informed about that.

> +		} else {
> +			i2c->speed_mode = HIX5I2C_NORMAL_SPD;
> +			i2c->s_clock = op_clock;
> +		}
> +	}
> +

...

> +	i2c->adap.owner   = THIS_MODULE;
> +	i2c->adap.algo	  = &hix5hd2_i2c_algorithm;

Single space as indentation.

Thanks,

   Wolfram