Re: [PATCH v2] i2c: add Marvell 64xxx driver

[Antony Pavlov <antonynpavlov@gmail.com>]

On Tue, 22 Jul 2014 10:51:10 +0200
Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> wrote:

> On 07/16/2014 11:25 PM, Antony Pavlov wrote:
> > This driver is also used for Allwinner SoCs I2C controllers.
> >
> > Ported from linux-3.15.
> >
> > The most notable barebox driver version changes:
> >
> >    * drop message offloading support;
> >    * add reg-io-width parameter to use driver with byte-oriented
> >      controller versions.
> >
> > Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
> 
> Antony,
> 
> I finally finished work on xHCI and PCI on Armada 370. Now I come
> back with the promised review of the i2c driver.
> 
> I gave this driver a quick test on Mirabox, i2c_probe just gives I2C bus
> errors. What SoC did you test the driver on?

I test it on custom FPGA-based byte-oriented mv64xxx-style i2c controller.

Linux 3.15 driver succesfully works with my controller. The only change is adding 
mv64xxx_write/mv64xxx_read functions for enabling byte registers access.

Have you probed your Mirabox i2c bus under linux?

> I'll now have a closer look at why it fails, but I already have some
> comments below.
> 
> > ---
> >   drivers/i2c/busses/Kconfig       |   8 +
> >   drivers/i2c/busses/Makefile      |   1 +
> >   drivers/i2c/busses/i2c-mv64xxx.c | 687 +++++++++++++++++++++++++++++++++++++++
> >   3 files changed, 696 insertions(+)
> >
> [...]
> > diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> > index 9823d1b..4e4f6ba 100644
> > --- a/drivers/i2c/busses/Makefile
> > +++ b/drivers/i2c/busses/Makefile
> > @@ -1,5 +1,6 @@
> >   obj-$(CONFIG_I2C_GPIO)		+= i2c-gpio.o
> >   obj-$(CONFIG_I2C_IMX) += i2c-imx.o
> > +obj-$(CONFIG_I2C_MV64XXX)	+= i2c-mv64xxx.o
> >   obj-$(CONFIG_I2C_OMAP) += i2c-omap.o
> 
> IMHO, you can also fixup the indention of i2c-imx.o and i2c-omap
> while you are at it.

I prefere using separate patch for fixing indentation.

> >   obj-$(CONFIG_I2C_TEGRA)		+= i2c-tegra.o
> >   obj-$(CONFIG_I2C_VERSATILE)	+= i2c-versatile.o
> > diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
> > new file mode 100644
> > index 0000000..324796a
> > --- /dev/null
> > +++ b/drivers/i2c/busses/i2c-mv64xxx.c
> > @@ -0,0 +1,687 @@
> > +/*
> > + * Driver for the i2c controller on the Marvell line of host bridges
> > + * (e.g, gt642[46]0, mv643[46]0, mv644[46]0, and Orion SoC family).
> 
>  From above list, it is more than unlikely that we will see support for
> any of the mv643foo devices. How about to rename the driver to
> i2c-orion, get rid of mv643foo, and add Allwinner SoCs to the list
> above?

I want to keep linux compatibility. This drivers has i2c-mv64xxx.c name in linux kernel!

> > + *
> > + * This code was ported from linux-3.15 kernel by Antony Pavlov.
> > + *
> > + * Author: Mark A. Greer <mgreer@mvista.com>
> > + *
> > + * 2005 (c) MontaVista, Software, Inc.  This file is licensed under
> > + * the terms of the GNU General Public License version 2.  This program
> > + * is licensed "as is" without any warranty of any kind, whether express
> > + * or implied.
> > + */
> > +#include <common.h>
> > +#include <driver.h>
> > +#include <init.h>
> > +#include <of.h>
> > +#include <malloc.h>
> > +#include <types.h>
> > +#include <xfuncs.h>
> > +#include <clock.h>
> > +#include <linux/clk.h>
> > +#include <linux/err.h>
> > +
> > +#include <io.h>
> > +#include <i2c/i2c.h>
> > +#include <printk.h>
> > +
> > +#define MV64XXX_I2C_ADDR_ADDR(val)			((val & 0x7f) << 1)
> > +#define MV64XXX_I2C_BAUD_DIV_N(val)			(val & 0x7)
> > +#define MV64XXX_I2C_BAUD_DIV_M(val)			((val & 0xf) << 3)
> > +
> > +#define	MV64XXX_I2C_REG_CONTROL_ACK			0x00000004
> > +#define	MV64XXX_I2C_REG_CONTROL_IFLG			0x00000008
> > +#define	MV64XXX_I2C_REG_CONTROL_STOP			0x00000010
> > +#define	MV64XXX_I2C_REG_CONTROL_START			0x00000020
> > +#define	MV64XXX_I2C_REG_CONTROL_TWSIEN			0x00000040
> > +#define	MV64XXX_I2C_REG_CONTROL_INTEN			0x00000080
> 
> As I said before, I see no point in tabs between #define and
> MV64XXX_FOO. It is not about the 80 column rule, but general
> style instead.
> 
> Also, you can use BIT(x) for above defines.

These are constants from linux kernel. I have only kept linux driver formatting.

> > +
> > +/* Ctlr status values */
> > +#define	MV64XXX_I2C_STATUS_BUS_ERR			0x00
> > +#define	MV64XXX_I2C_STATUS_MAST_START			0x08
> > +#define	MV64XXX_I2C_STATUS_MAST_REPEAT_START		0x10
> > +#define	MV64XXX_I2C_STATUS_MAST_WR_ADDR_ACK		0x18
> > +#define	MV64XXX_I2C_STATUS_MAST_WR_ADDR_NO_ACK		0x20
> > +#define	MV64XXX_I2C_STATUS_MAST_WR_ACK			0x28
> > +#define	MV64XXX_I2C_STATUS_MAST_WR_NO_ACK		0x30
> > +#define	MV64XXX_I2C_STATUS_MAST_LOST_ARB		0x38
> > +#define	MV64XXX_I2C_STATUS_MAST_RD_ADDR_ACK		0x40
> > +#define	MV64XXX_I2C_STATUS_MAST_RD_ADDR_NO_ACK		0x48
> > +#define	MV64XXX_I2C_STATUS_MAST_RD_DATA_ACK		0x50
> > +#define	MV64XXX_I2C_STATUS_MAST_RD_DATA_NO_ACK		0x58
> > +#define	MV64XXX_I2C_STATUS_MAST_WR_ADDR_2_ACK		0xd0
> > +#define	MV64XXX_I2C_STATUS_MAST_WR_ADDR_2_NO_ACK	0xd8
> > +#define	MV64XXX_I2C_STATUS_MAST_RD_ADDR_2_ACK		0xe0
> > +#define	MV64XXX_I2C_STATUS_MAST_RD_ADDR_2_NO_ACK	0xe8
> > +#define	MV64XXX_I2C_STATUS_NO_STATUS			0xf8
> > +
> > +/* Driver states */
> > +enum {
> 
> enum mv64xxx_state {
> 
> and get rid of MV64XXX_I2C_ prefix below.
> 
> > +	MV64XXX_I2C_STATE_INVALID,
> > +	MV64XXX_I2C_STATE_IDLE,
> > +	MV64XXX_I2C_STATE_WAITING_FOR_START_COND,
> > +	MV64XXX_I2C_STATE_WAITING_FOR_RESTART,
> > +	MV64XXX_I2C_STATE_WAITING_FOR_ADDR_1_ACK,
> > +	MV64XXX_I2C_STATE_WAITING_FOR_ADDR_2_ACK,
> > +	MV64XXX_I2C_STATE_WAITING_FOR_SLAVE_ACK,
> > +	MV64XXX_I2C_STATE_WAITING_FOR_SLAVE_DATA,
> > +};
> > +
> > +/* Driver actions */
> > +enum {
> 
> enum mv64xxx_action {
> 
> and get rid of MV64XXX_I2C_ prefix below.
> 
> > +	MV64XXX_I2C_ACTION_INVALID,
> > +	MV64XXX_I2C_ACTION_CONTINUE,
> > +	MV64XXX_I2C_ACTION_SEND_RESTART,
> > +	MV64XXX_I2C_ACTION_OFFLOAD_RESTART,
> > +	MV64XXX_I2C_ACTION_SEND_ADDR_1,
> > +	MV64XXX_I2C_ACTION_SEND_ADDR_2,
> > +	MV64XXX_I2C_ACTION_SEND_DATA,
> > +	MV64XXX_I2C_ACTION_RCV_DATA,
> > +	MV64XXX_I2C_ACTION_RCV_DATA_STOP,
> > +	MV64XXX_I2C_ACTION_SEND_STOP,
> > +	MV64XXX_I2C_ACTION_OFFLOAD_SEND_STOP,
> > +};
> > +
> > +struct mv64xxx_i2c_regs {
> > +	u8	addr;
> > +	u8	ext_addr;
> > +	u8	data;
> > +	u8	control;
> > +	u8	status;
> > +	u8	clock;
> > +	u8	soft_reset;
> > +};
> > +
> > +struct mv64xxx_i2c_data {
> > +	struct i2c_msg		*msgs;
> > +	int			num_msgs;
> > +	u32			state;
> > +	u32			action;
> 
> enum mv64xxx_state state;
> enum mv64xxx_action action;

Good idea!

> > +	u32			aborting;
> 
> You are never aborting, so get rid of it and the logic completely.


You are right, drv_data->aborting is always == 0.

> > +	u32			cntl_bits;
> 
> u8 cntl_bits;
> 
> Although Orion SoCs allow 32b access, the registers are always
> 8b.

That is why FPGA-based i2c-controller that I work with byte oriented register access is used!

> > +	void __iomem		*reg_base;
> 
> If you struggle with long lines, '*regs' or '*base' is sufficient.
> 
> > +	struct mv64xxx_i2c_regs	reg_offsets;
> 
> ditto, just choose shorter names.

Linux kernel driver use this names. I prefer to use them too.

> > +	u32			addr1;
> > +	u32			addr2;
> 
> If you want to keep the state machine and track all msg stuff,
> u8 is enough for both addrN above.
> 
> > +	u32			bytes_left;
> > +	u32			byte_posn;
> 
> ditto, IIRC i2c doesn't even allow you to send more than 255 bytes
> per message nor will you ever find a device that supports it.
> 
> > +	u32			send_stop;
> 
> I wonder if you'll ever send a restart at all, that will leave
> the stop to the last message transferred. In any way, above should
> be bool.
> 
> > +	u32			block;
> 
> Whatever block is for, remember that you will send each byte
> individually and you'll ever be in charge of the code, i.e.
> if you wait for completion, barebox will wait for it.
> There is no threading nor interrupts.
> 
> > +	int			rc;
> > +	u32			freq_m;
> > +	u32			freq_n;
> 
> You could just init the HW when you found the best dividers.
> No need to store them for eternity.
> 
> > +	struct clk              *clk;
> > +	struct i2c_msg		*msg;
> > +	struct i2c_adapter	adapter;
> > +/* 5us delay in order to avoid repeated start timing violation */
> > +	bool			errata_delay;
> > +	struct reset_control	*rstc;
> 
> Unused.
> 
> > +	bool			irq_clear_inverted;
> > +	int			reg_io_width;
> > +};
> > +
> > +static struct mv64xxx_i2c_regs mv64xxx_i2c_regs_mv64xxx = {
> 
> __maybe_unused and see below at compatibles table.
> 
> > +	.addr		= 0x00,
> > +	.ext_addr	= 0x10,
> > +	.data		= 0x04,
> > +	.control	= 0x08,
> > +	.status		= 0x0c,
> > +	.clock		= 0x0c,
> > +	.soft_reset	= 0x1c,
> > +};
> > +
> > +static struct mv64xxx_i2c_regs mv64xxx_i2c_regs_sun4i = {
> 
> ditto.

Agree. Also I think I can convert u32 to u8 as you have noted above.

> > +	.addr		= 0x00,
> > +	.ext_addr	= 0x04,
> > +	.data		= 0x08,
> > +	.control	= 0x0c,
> > +	.status		= 0x10,
> > +	.clock		= 0x14,
> > +	.soft_reset	= 0x18,
> > +};
> > +
> > +static inline void mv64xxx_write(struct mv64xxx_i2c_data *drv_data, u32 v, int reg)
> 
> How about having a callback for this and _read below?
> 
> You'd install the callback in _probe() and get rid of reg_io_width
> check for every read/write access, i.e
> 
> static void mv64xxx_writel(...)
> {
> 	writel(v, addr);
> }
> 
> static void mv64xxx_writeb(...)
> {
> 	writeb(v, addr);
> }
> 
> static int mv64xxx_i2c_probe(...)
> {
> 	...
> 
> 	switch (reg_io_width) {
> 	case 1:
> 		drv_data->read = mv64xxx_readb;
> 		drv_data->write = mv64xxx_writeb;
> 		break;
> 	case 4:
> 		drv_data->read = mv64xxx_readl;
> 		drv_data->write = mv64xxx_writel;
> 		break;
> 	default:
> 		dev_err(pd, "unsupported reg-io-width (%d)\n",
> 			reg_io_width);
> 		rc = -EINVAL;
> 		goto out;
> 	}
> 
> 	...
> }
> 
> > +{
> > +	void *addr = drv_data->reg_base + reg;
> > +
> > +	switch (drv_data->reg_io_width) {
> > +	case IORESOURCE_MEM_8BIT:
> > +		writeb((u8)v, addr);
> > +		break;
> > +	case IORESOURCE_MEM_32BIT:
> > +		writel(v, addr);
> > +		break;
> > +	default:
> > +		dev_err(&drv_data->adapter.dev,
> > +			"%s: wrong reg_io_width!\n", __func__);
> 
> Beside the comment above, you already made sure reg_io_width will
> never be anything else than 8BIT or 32BIT. So the default case is
> not needed at all.

good I can change it to callback. I see a template in drivers/serial/serial_ns16550.c.

> > +	}
> > +}
> > +
> > +static inline u32 mv64xxx_read(struct mv64xxx_i2c_data *drv_data, int reg)
> > +{
> > +	void *addr = drv_data->reg_base + reg;
> > +	u32 r;
> > +
> > +	switch (drv_data->reg_io_width) {
> > +	case IORESOURCE_MEM_8BIT:
> > +		r = readb(addr);
> > +		break;
> > +
> > +	case IORESOURCE_MEM_32BIT:
> > +		r = readl(addr);
> > +		break;
> > +
> > +	default:
> > +		dev_err(&drv_data->adapter.dev,
> > +			"%s: wrong reg_io_width!\n", __func__);
> > +		r = 0xffffffff;
> > +	}
> > +
> > +	return r;
> > +}
> > +
> > +static void
> > +mv64xxx_i2c_prepare_for_io(struct mv64xxx_i2c_data *drv_data,
> > +	struct i2c_msg *msg)
> > +{
> > +	u32	dir = 0;
> > +
> > +	drv_data->cntl_bits = MV64XXX_I2C_REG_CONTROL_ACK |
> > +		MV64XXX_I2C_REG_CONTROL_INTEN | MV64XXX_I2C_REG_CONTROL_TWSIEN;
> > +
> > +	if (msg->flags & I2C_M_RD)
> > +		dir = 1;
> > +
> > +	if (msg->flags & I2C_M_TEN) {
> > +		drv_data->addr1 = 0xf0 | (((u32)msg->addr & 0x300) >> 7) | dir;
> > +		drv_data->addr2 = (u32)msg->addr & 0xff;
> > +	} else {
> > +		drv_data->addr1 = MV64XXX_I2C_ADDR_ADDR((u32)msg->addr) | dir;
> > +		drv_data->addr2 = 0;
> > +	}
> > +}
> > +
> > +/*
> > + *****************************************************************************
> > + *
> > + *	Finite State Machine & Interrupt Routines
> > + *
> > + *****************************************************************************
> > + */
> > +
> > +/* Reset hardware and initialize FSM */
> > +static void
> > +mv64xxx_i2c_hw_init(struct mv64xxx_i2c_data *drv_data)
> > +{
> > +	mv64xxx_write(drv_data, 0, drv_data->reg_offsets.soft_reset);
> > +	mv64xxx_write(drv_data, MV64XXX_I2C_BAUD_DIV_M(drv_data->freq_m) | MV64XXX_I2C_BAUD_DIV_N(drv_data->freq_n),
> > +		drv_data->reg_offsets.clock);
> > +	mv64xxx_write(drv_data, 0, drv_data->reg_offsets.addr);
> > +	mv64xxx_write(drv_data, 0, drv_data->reg_offsets.ext_addr);
> > +	mv64xxx_write(drv_data, MV64XXX_I2C_REG_CONTROL_TWSIEN | MV64XXX_I2C_REG_CONTROL_STOP,
> > +		drv_data->reg_offsets.control);
> > +	drv_data->state = MV64XXX_I2C_STATE_IDLE;
> > +}
> > +
> > +static void
> > +mv64xxx_i2c_fsm(struct mv64xxx_i2c_data *drv_data, u32 status)
> > +{
> > +	/*
> > +	 * If state is idle, then this is likely the remnants of an old
> > +	 * operation that driver has given up on or the user has killed.
> > +	 * If so, issue the stop condition and go to idle.
> > +	 */
> > +	if (drv_data->state == MV64XXX_I2C_STATE_IDLE) {
> > +		drv_data->action = MV64XXX_I2C_ACTION_SEND_STOP;
> > +		return;
> > +	}
> > +
> > +	/* The status from the ctlr [mostly] tells us what to do next */
> > +	switch (status) {
> > +	/* Start condition interrupt */
> > +	case MV64XXX_I2C_STATUS_MAST_START: /* 0x08 */
> > +	case MV64XXX_I2C_STATUS_MAST_REPEAT_START: /* 0x10 */
> > +		drv_data->action = MV64XXX_I2C_ACTION_SEND_ADDR_1;
> > +		drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_ADDR_1_ACK;
> > +		break;
> > +
> > +	/* Performing a write */
> > +	case MV64XXX_I2C_STATUS_MAST_WR_ADDR_ACK: /* 0x18 */
> > +		if (drv_data->msg->flags & I2C_M_TEN) {
> > +			drv_data->action = MV64XXX_I2C_ACTION_SEND_ADDR_2;
> > +			drv_data->state =
> > +				MV64XXX_I2C_STATE_WAITING_FOR_ADDR_2_ACK;
> > +			break;
> > +		}
> > +		/* FALLTHRU */
> > +	case MV64XXX_I2C_STATUS_MAST_WR_ADDR_2_ACK: /* 0xd0 */
> > +	case MV64XXX_I2C_STATUS_MAST_WR_ACK: /* 0x28 */
> > +		if ((drv_data->bytes_left == 0)
> > +				|| (drv_data->aborting
> > +					&& (drv_data->byte_posn != 0))) {
> > +			if (drv_data->send_stop || drv_data->aborting) {
> > +				drv_data->action = MV64XXX_I2C_ACTION_SEND_STOP;
> > +				drv_data->state = MV64XXX_I2C_STATE_IDLE;
> > +			} else {
> > +				drv_data->action =
> > +					MV64XXX_I2C_ACTION_SEND_RESTART;
> > +				drv_data->state =
> > +					MV64XXX_I2C_STATE_WAITING_FOR_RESTART;
> > +			}
> > +		} else {
> > +			drv_data->action = MV64XXX_I2C_ACTION_SEND_DATA;
> > +			drv_data->state =
> > +				MV64XXX_I2C_STATE_WAITING_FOR_SLAVE_ACK;
> > +			drv_data->bytes_left--;
> > +		}
> > +		break;
> > +
> > +	/* Performing a read */
> > +	case MV64XXX_I2C_STATUS_MAST_RD_ADDR_ACK: /* 40 */
> > +		if (drv_data->msg->flags & I2C_M_TEN) {
> > +			drv_data->action = MV64XXX_I2C_ACTION_SEND_ADDR_2;
> > +			drv_data->state =
> > +				MV64XXX_I2C_STATE_WAITING_FOR_ADDR_2_ACK;
> > +			break;
> > +		}
> > +		/* FALLTHRU */
> > +	case MV64XXX_I2C_STATUS_MAST_RD_ADDR_2_ACK: /* 0xe0 */
> > +		if (drv_data->bytes_left == 0) {
> > +			drv_data->action = MV64XXX_I2C_ACTION_SEND_STOP;
> > +			drv_data->state = MV64XXX_I2C_STATE_IDLE;
> > +			break;
> > +		}
> > +		/* FALLTHRU */
> > +	case MV64XXX_I2C_STATUS_MAST_RD_DATA_ACK: /* 0x50 */
> > +		if (status != MV64XXX_I2C_STATUS_MAST_RD_DATA_ACK)
> > +			drv_data->action = MV64XXX_I2C_ACTION_CONTINUE;
> > +		else {
> > +			drv_data->action = MV64XXX_I2C_ACTION_RCV_DATA;
> > +			drv_data->bytes_left--;
> > +		}
> > +		drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_SLAVE_DATA;
> > +
> > +		if ((drv_data->bytes_left == 1) || drv_data->aborting)
> > +			drv_data->cntl_bits &= ~MV64XXX_I2C_REG_CONTROL_ACK;
> > +		break;
> > +
> > +	case MV64XXX_I2C_STATUS_MAST_RD_DATA_NO_ACK: /* 0x58 */
> > +		drv_data->action = MV64XXX_I2C_ACTION_RCV_DATA_STOP;
> > +		drv_data->state = MV64XXX_I2C_STATE_IDLE;
> > +		break;
> > +
> > +	case MV64XXX_I2C_STATUS_MAST_WR_ADDR_NO_ACK: /* 0x20 */
> > +	case MV64XXX_I2C_STATUS_MAST_WR_NO_ACK: /* 30 */
> > +	case MV64XXX_I2C_STATUS_MAST_RD_ADDR_NO_ACK: /* 48 */
> > +		/* Doesn't seem to be a device at other end */
> > +		drv_data->action = MV64XXX_I2C_ACTION_SEND_STOP;
> > +		drv_data->state = MV64XXX_I2C_STATE_IDLE;
> > +		drv_data->rc = -ENXIO;
> > +		break;
> > +
> > +	default:
> > +		dev_err(&drv_data->adapter.dev,
> > +			"mv64xxx_i2c_fsm: Ctlr Error -- state: 0x%x, "
> > +			"status: 0x%x, addr: 0x%x, flags: 0x%x\n",
> > +			 drv_data->state, status, drv_data->msg->addr,
> > +			 drv_data->msg->flags);
> > +		drv_data->action = MV64XXX_I2C_ACTION_SEND_STOP;
> > +		mv64xxx_i2c_hw_init(drv_data);
> > +		drv_data->rc = -EIO;
> > +	}
> > +}
> > +
> > +static void mv64xxx_i2c_send_start(struct mv64xxx_i2c_data *drv_data)
> > +{
> > +	drv_data->msg = drv_data->msgs;
> > +	drv_data->byte_posn = 0;
> > +	drv_data->bytes_left = drv_data->msg->len;
> > +	drv_data->aborting = 0;
> > +	drv_data->rc = 0;
> > +
> > +	mv64xxx_i2c_prepare_for_io(drv_data, drv_data->msgs);
> > +	mv64xxx_write(drv_data, drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_START,
> > +		drv_data->reg_offsets.control);
> > +}
> > +
> > +static void
> > +mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
> > +{
> > +	switch (drv_data->action) {
> > +	case MV64XXX_I2C_ACTION_SEND_RESTART:
> > +		/* We should only get here if we have further messages */
> > +		BUG_ON(drv_data->num_msgs == 0);
> > +
> > +		drv_data->msgs++;
> > +		drv_data->num_msgs--;
> > +		mv64xxx_i2c_send_start(drv_data);
> > +
> > +		if (drv_data->errata_delay)
> > +			udelay(5);
> > +
> > +		/*
> > +		 * We're never at the start of the message here, and by this
> > +		 * time it's already too late to do any protocol mangling.
> > +		 * Thankfully, do not advertise support for that feature.
> > +		 */
> > +		drv_data->send_stop = drv_data->num_msgs == 1;
> > +		break;
> > +
> > +	case MV64XXX_I2C_ACTION_CONTINUE:
> > +		mv64xxx_write(drv_data, drv_data->cntl_bits,
> > +			drv_data->reg_offsets.control);
> > +		break;
> > +
> > +	case MV64XXX_I2C_ACTION_SEND_ADDR_1:
> > +		mv64xxx_write(drv_data, drv_data->addr1,
> > +			drv_data->reg_offsets.data);
> > +		mv64xxx_write(drv_data, drv_data->cntl_bits,
> > +			drv_data->reg_offsets.control);
> > +		break;
> > +
> > +	case MV64XXX_I2C_ACTION_SEND_ADDR_2:
> > +		mv64xxx_write(drv_data, drv_data->addr2,
> > +			drv_data->reg_offsets.data);
> > +		mv64xxx_write(drv_data, drv_data->cntl_bits,
> > +			drv_data->reg_offsets.control);
> > +		break;
> > +
> > +	case MV64XXX_I2C_ACTION_SEND_DATA:
> > +		mv64xxx_write(drv_data, drv_data->msg->buf[drv_data->byte_posn++],
> > +			drv_data->reg_offsets.data);
> > +		mv64xxx_write(drv_data, drv_data->cntl_bits,
> > +			drv_data->reg_offsets.control);
> > +		break;
> > +
> > +	case MV64XXX_I2C_ACTION_RCV_DATA:
> > +		drv_data->msg->buf[drv_data->byte_posn++] =
> > +			mv64xxx_read(drv_data, drv_data->reg_offsets.data);
> > +		mv64xxx_write(drv_data, drv_data->cntl_bits,
> > +			drv_data->reg_offsets.control);
> > +		break;
> > +
> > +	case MV64XXX_I2C_ACTION_RCV_DATA_STOP:
> > +		drv_data->msg->buf[drv_data->byte_posn++] =
> > +			mv64xxx_read(drv_data, drv_data->reg_offsets.data);
> > +		drv_data->cntl_bits &= ~MV64XXX_I2C_REG_CONTROL_INTEN;
> > +		mv64xxx_write(drv_data, drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_STOP,
> > +			drv_data->reg_offsets.control);
> > +		drv_data->block = 0;
> > +		if (drv_data->errata_delay)
> > +			udelay(5);
> > +
> > +		break;
> > +
> > +	case MV64XXX_I2C_ACTION_INVALID:
> > +	default:
> > +		dev_err(&drv_data->adapter.dev,
> > +			"mv64xxx_i2c_do_action: Invalid action: %d\n",
> > +			drv_data->action);
> > +		drv_data->rc = -EIO;
> > +
> > +		/* FALLTHRU */
> > +	case MV64XXX_I2C_ACTION_SEND_STOP:
> > +		drv_data->cntl_bits &= ~MV64XXX_I2C_REG_CONTROL_INTEN;
> > +		mv64xxx_write(drv_data, drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_STOP,
> > +			drv_data->reg_offsets.control);
> > +		drv_data->block = 0;
> > +		break;
> > +	}
> > +}
> > +
> > +static void mv64xxx_i2c_intr(struct mv64xxx_i2c_data *drv_data)
> 
> Is "intr" for interrupt? Barebox is running with irqs disabled, so
> maybe rename it to something like "mv64xxx_i2c_wait_for_done" ?

This functions makes the work of the driver interrupt handler, so I prefere to keep
linux kernel compartible naming here.

> > +{
> > +	u32 status;
> > +	uint64_t start;
> > +
> > +	start = get_time_ns();
> > +
> > +	while (mv64xxx_read(drv_data, drv_data->reg_offsets.control) &
> > +						MV64XXX_I2C_REG_CONTROL_IFLG) {
> > +		status = mv64xxx_read(drv_data, drv_data->reg_offsets.status);
> > +		mv64xxx_i2c_fsm(drv_data, status);
> > +		mv64xxx_i2c_do_action(drv_data);
> > +
> > +		if (drv_data->irq_clear_inverted)
> > +			mv64xxx_write(drv_data, drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_IFLG,
> > +			       drv_data->reg_offsets.control);
> > +
> > +		if (is_timeout_non_interruptible(start, 3 * SECOND)) {
> > +			drv_data->rc = -EIO;
> > +			break;
> > +		}
> > +	}
> > +}
> > +
> > +/*
> > + *****************************************************************************
> > + *
> > + *	I2C Msg Execution Routines
> > + *
> > + *****************************************************************************
> > + */
> > +static void
> > +mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
> > +{
> > +	do {
> > +		mv64xxx_i2c_intr(drv_data);
> > +		if (drv_data->rc) {
> > +			drv_data->state = MV64XXX_I2C_STATE_IDLE;
> > +			dev_err(&drv_data->adapter.dev, "I2C bus error\n");
> > +			mv64xxx_i2c_hw_init(drv_data);
> > +			drv_data->block = 0;
> > +		}
> > +	} while (drv_data->block != 0);
> > +}
> > +
> > +static int
> > +mv64xxx_i2c_execute_msg(struct mv64xxx_i2c_data *drv_data, struct i2c_msg *msg,
> > +				int is_last)
> > +{
> > +	drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
> > +
> > +	drv_data->send_stop = is_last;
> > +	drv_data->block = 1;
> > +	mv64xxx_i2c_send_start(drv_data);
> > +	mv64xxx_i2c_wait_for_completion(drv_data);
> > +
> > +	return drv_data->rc;
> > +}
> > +
> > +/*
> > + *****************************************************************************
> > + *
> > + *	I2C Core Support Routines (Interface to higher level I2C code)
> > + *
> > + *****************************************************************************
> > + */
> > +static int
> > +mv64xxx_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> > +{
> > +	struct mv64xxx_i2c_data *drv_data = container_of(adap, struct mv64xxx_i2c_data, adapter);
> > +	int rc, ret = num;
> > +
> > +	BUG_ON(drv_data->msgs != NULL);
> > +	drv_data->msgs = msgs;
> > +	drv_data->num_msgs = num;
> > +
> > +	rc = mv64xxx_i2c_execute_msg(drv_data, &msgs[0], num == 1);
> > +	if (rc < 0)
> > +		ret = rc;
> > +
> > +	drv_data->num_msgs = 0;
> > +	drv_data->msgs = NULL;
> 
> How about you loop over all passed msgs in here and get rid of
> the both drv_data variables completely?

I don't want to change code from linux driver without very good reason.

> 
> > +
> > +	return ret;
> > +}
> > +
> > +/*
> > + *****************************************************************************
> > + *
> > + *	Driver Interface & Early Init Routines
> > + *
> > + *****************************************************************************
> > + */
> > +static struct of_device_id mv64xxx_i2c_of_match_table[] = {
> #if defined(CONFIG_SUN4I_FOO)
> > +	{ .compatible = "allwinner,sun4i-i2c", .data = (unsigned long)&mv64xxx_i2c_regs_sun4i},
> #endif
> #if defined(CONFIG_SUN6I_FOO)
> > +	{ .compatible = "allwinner,sun6i-a31-i2c", .data = (unsigned long)&mv64xxx_i2c_regs_sun4i},
> #endif
> #if defined(CONFIG_MACH_MVEBU)
> > +	{ .compatible = "marvell,mv64xxx-i2c", .data = (unsigned long)&mv64xxx_i2c_regs_mv64xxx},
> #endif
> #if defined(CONFIG_ARCH_ARMADA_XP)
> > +	{ .compatible = "marvell,mv78230-i2c", .data = (unsigned long)&mv64xxx_i2c_regs_mv64xxx},
> > +	{ .compatible = "marvell,mv78230-a0-i2c", .data = (unsigned long)&mv64xxx_i2c_regs_mv64xxx},
> #endif
> > +	{}
> > +};
> 
> If you ifdef the compatibles, the compiler will be able to remove all
> structs that are not referenced.
> 
> > +
> > +static int
> > +mv64xxx_calc_freq(const int tclk, const int n, const int m)
> 
> inline?

Yes!

> > +{
> > +	return tclk / (10 * (m + 1) * (2 << n));
> > +}
> > +
> > +static bool
> > +mv64xxx_find_baud_factors(const u32 req_freq, const u32 tclk, u32 *best_n,
> > +			  u32 *best_m)
> > +{
> > +	int freq, delta, best_delta = INT_MAX;
> > +	int m, n;
> > +
> > +	for (n = 0; n <= 7; n++)
> > +		for (m = 0; m <= 15; m++) {
> > +			freq = mv64xxx_calc_freq(tclk, n, m);
> > +			delta = req_freq - freq;
> > +			if (delta >= 0 && delta < best_delta) {
> > +				*best_m = m;
> > +				*best_n = n;
> > +				best_delta = delta;
> > +			}
> > +			if (best_delta == 0)
> > +				return true;
> > +		}
> > +	if (best_delta == INT_MAX)
> > +		return false;
> > +	return true;
> > +}
> > +
> > +static int
> > +mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
> > +		  struct device_d *pd)
> > +{
> > +	struct device_node *np = pd->device_node;
> > +	u32 bus_freq, tclk;
> > +	int rc = 0;
> > +	u32 prop;
> > +	struct mv64xxx_i2c_regs *mv64xxx_regs;
> > +	int freq;
> > +
> > +	if (IS_ERR(drv_data->clk)) {
> > +		rc = -ENODEV;
> > +		goto out;
> > +	}
> > +	tclk = clk_get_rate(drv_data->clk);
> > +
> > +	rc = of_property_read_u32(np, "clock-frequency", &bus_freq);
> > +	if (rc)
> > +		bus_freq = 100000; /* 100kHz by default */
> > +
> > +	if (!mv64xxx_find_baud_factors(bus_freq, tclk,
> > +				       &drv_data->freq_n, &drv_data->freq_m)) {
> > +		rc = -EINVAL;
> > +		goto out;
> > +	}
> > +
> > +	freq = mv64xxx_calc_freq(tclk, drv_data->freq_n, drv_data->freq_m);
> > +	dev_dbg(pd, "tclk=%d freq_n=%d freq_m=%d freq=%d\n",
> > +			tclk, drv_data->freq_n, drv_data->freq_m, freq);
> > +
> > +	drv_data->reg_io_width = IORESOURCE_MEM_32BIT;
> > +
> > +	if (of_property_read_u32(np, "reg-io-width", &prop) == 0) {
> > +		switch (prop) {
> > +		case 1:
> > +			drv_data->reg_io_width = IORESOURCE_MEM_8BIT;
> > +			break;
> > +		case 4:
> > +			drv_data->reg_io_width = IORESOURCE_MEM_32BIT;
> > +			break;
> > +		default:
> > +			dev_err(pd, "unsupported reg-io-width (%d)\n", prop);
> > +			rc = -EINVAL;
> > +			goto out;
> > +		}
> > +	}
> > +
> > +	dev_get_drvdata(pd, (unsigned long *)&mv64xxx_regs);
> > +	memcpy(&drv_data->reg_offsets, mv64xxx_regs,
> > +		sizeof(drv_data->reg_offsets));
> > +
> > +	/*
> > +	 * For controllers embedded in new SoCs activate the
> > +	 * Transaction Generator support and the errata fix.
> > +	 */
> > +	if (of_device_is_compatible(np, "marvell,mv78230-i2c")) {
> > +		drv_data->errata_delay = true;
> > +	}
> 
> You can get rid of the {}'s
> 
> > +
> > +	if (of_device_is_compatible(np, "marvell,mv78230-a0-i2c")) {
> > +		drv_data->errata_delay = true;
> > +	}
> > +
> > +	if (of_device_is_compatible(np, "allwinner,sun6i-a31-i2c"))
> > +		drv_data->irq_clear_inverted = true;
> > +
> > +out:
> > +	return rc;
> > +}
> > +
> > +static int
> > +mv64xxx_i2c_probe(struct device_d *pd)
> > +{
> > +	struct mv64xxx_i2c_data		*drv_data;
> > +	int	rc;
> > +
> > +	if (!pd->device_node)
> > +		return -ENODEV;
> > +
> > +	drv_data = xzalloc(sizeof(*drv_data));
> > +
> > +	drv_data->reg_base = dev_request_mem_region(pd, 0);
> > +	if (IS_ERR(drv_data->reg_base))
> > +		return PTR_ERR(drv_data->reg_base);
> > +
> > +	drv_data->clk = clk_get(pd, NULL);
> > +	if (IS_ERR(drv_data->clk))
> > +		return PTR_ERR(drv_data->clk);
> > +
> > +	clk_enable(drv_data->clk);
> > +
> > +	rc = mv64xxx_of_config(drv_data, pd);
> > +	if (rc)
> > +		goto exit_clk;
> > +
> > +	drv_data->adapter.master_xfer = mv64xxx_i2c_xfer;
> > +	drv_data->adapter.dev.parent = pd;
> > +	drv_data->adapter.nr = pd->id;
> > +	drv_data->adapter.dev.device_node = pd->device_node;
> > +
> > +	mv64xxx_i2c_hw_init(drv_data);
> > +
> > +	rc = i2c_add_numbered_adapter(&drv_data->adapter);
> > +	if (rc) {
> > +		dev_err(pd, "Failed to add I2C adapter\n");
> > +		goto exit_clk;
> > +	}
> > +
> > +	return 0;
> > +
> > +exit_clk:
> > +	clk_disable(drv_data->clk);
> > +
> > +	return rc;
> > +}
> > +
> > +static struct driver_d mv64xxx_i2c_driver = {
> > +	.probe	= mv64xxx_i2c_probe,
> > +	.name = "mv64xxx_i2c",
> > +	.of_compatible = DRV_OF_COMPAT(mv64xxx_i2c_of_match_table),
> > +};
> > +device_platform_driver(mv64xxx_i2c_driver);
> >
> 
> In general, I agree that picking the driver from Linux is a good idea
> because it is tested already. But IMHO there is often a huge amount of
> unnecessary abstraction included that should be considered again for a
> bootloader driver.
> 
> I haven't looked at any detail of the FSM in this driver, but maybe it
> is a victim for cleanup?

I'll try to fix most of your issues.

I think that it is better to use the same driver in linux and barebox.
There is no reason to fix barebox driver without fixing original linux driver.

-- 
Best regards,
  Antony Pavlov

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