Re: SPI bitbang master for TV cards

Re: SPI bitbang master for TV cards

[Grant Likely]

On Tue, Nov 24, 2009 at 12:22 AM, Dmitri Belimov <d.belimov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Hi Grant
>
> I found you mails about SPI subsystem. Can you help me?
> I write some support for our TV cards (open source of course)
> One of them has hardware MPEG2 encoder connected to host chip
> via GPIO. In our windows drivers we wrote internal simple SPI bitbang
> driver. For Linux we want use generic SPI subsystem.
> I wrote my ugly code, not working yet.
>
> If it's intresting for you I'll send it.

Post your details and questions to the
spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org mailing list.  That's probably
the best way to get help.

Alternately if you need commercial support, my company provides both
consulting and engineering services to help get your driver written.
Let me know if you want details.

Cheers,
g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

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SPI bitbang master for TV cards

[Dmitri Belimov]

Hi All.

I write some support for our TV cards (open source of course)
One of them has hardware MPEG2 encoder connected to host chip
via GPIO. In our windows drivers we wrote internal simple SPI bitbang
driver. For Linux we want use generic SPI subsystem.
I wrote my ugly code, not working yet.


#include "saa7134-reg.h"
#include "saa7134.h"
#include <media/v4l2-common.h>

/* ----------------------------------------------------------- */

static unsigned int spi_debug;
module_param(spi_debug, int, 0644);
MODULE_PARM_DESC(spi_debug,"enable debug messages [spi]");

#define d1printk if (1 == spi_debug) printk
#define d2printk if (2 == spi_debug) printk

static inline struct saa7134_spi_gpio *to_sb(struct spi_device *spi)
{
	return spi_master_get_devdata(spi->master);
}

static inline void setsck(struct spi_device *dev, int on)
{
	struct saa7134_spi_gpio *sb = to_sb(dev);

	saa7134_set_gpio(sb->controller_data, sb->controller_data->spi.clock, on ? 1 : 0);
}

static inline void setmosi(struct spi_device *dev, int on)
{
	struct saa7134_spi_gpio *sb = to_sb(dev);

	saa7134_set_gpio(sb->controller_data, sb->controller_data->spi.mosi, on ? 1 : 0);
}

static inline u32 getmiso(struct spi_device *dev)
{
	struct saa7134_spi_gpio *sb = to_sb(dev);
	unsigned long status;

	status = saa7134_get_gpio(sb->controller_data);
	if ( status & (1 << sb->controller_data->spi.miso)) return 1;
	else
		return 0;
}

static void saa7134_spi_gpio_chipsel(struct spi_device *dev, int on)
{
	struct saa7134_spi_gpio *sb = to_sb(dev);

	saa7134_set_gpio(sb->controller_data, sb->controller_data->spi.cs, on ? 1 : 0);
}

int saa7134_spi_register(struct saa7134_dev *dev)
{
	struct spi_master *master = dev->spi_adap.master;
	struct saa7134_spi_gpio *sb = &dev->spi_adap;
	int ret = 0;

printk("SPI register start\n");

	if (!dev->spi.spi_enable)
	{
	printk("SPI is not configured\n");
		return 0;
	}

	master = spi_alloc_master(&dev->spi_adap.pdev->dev, sizeof(struct saa7134_spi_gpio));

	if (master == NULL) {
		dev_err(&dev->spi_adap.pdev->dev, "failed to allocate spi master\n");
		ret = -ENOMEM;
		goto err;
	}

	sb = spi_master_get_devdata(master);

	master->num_chipselect = dev->spi.num_chipselect;
	master->bus_num = -1;

	sb->master = spi_master_get(master);

	sb->bitbang.master = sb->master;
	sb->bitbang.master->bus_num = -1;
	sb->bitbang.chipselect = saa7134_spi_gpio_chipsel;
	sb->bitbang.master->num_chipselect = dev->spi.num_chipselect;

	/* set state of spi pins */
	saa7134_set_gpio(dev, dev->spi.cs, 1);
	saa7134_set_gpio(dev, dev->spi.clock, 1);
	saa7134_set_gpio(dev, dev->spi.mosi, 1);
	saa7134_set_gpio(dev, dev->spi.miso, 3);

//	drv_set_drvdata(&sb->master->dev, sb);

	ret = spi_bitbang_start(&sb->bitbang);

	if (ret) {
		dev_err(&dev->spi_adap.pdev->dev, "Failed to register SPI master\n");
		goto err_no_bitbang;
	}

	dev_info(&dev->spi_adap.pdev->dev,
		"spi master registered: bus_num=%d num_chipselect=%d\n",
		master->bus_num, master->num_chipselect);

	sb->controller_data = dev;
printk("SPI register stop and OK\n");
	return 0;

err_no_bitbang:
	spi_master_put(&sb->bitbang.master);
err:
printk("SPI register stop and FAIL\n");
	return ret;
}

int saa7134_spi_unregister(struct saa7134_dev *dev)
{
	spi_bitbang_stop(&dev->spi_adap.bitbang);
	spi_master_put(&dev->spi_adap.bitbang.master);
	return 0;
}


Some structures from saa7134.h

Structure for store config of GPIO
struct saa7134_software_spi {
	unsigned char cs:5;
	unsigned char clock:5;
	unsigned char mosi:5;
	unsigned char miso:5;
	unsigned char num_chipselect:3;
	unsigned char spi_enable:1;
};

Structure for SPI controller
struct saa7134_spi_gpio {
	struct spi_bitbang	bitbang;
	struct spi_master	*master;
	struct platform_device	*pdev;
	struct saa7134_dev	*controller_data;
};

/* global device status */
struct saa7134_dev {

skip

	/* software spi */
	struct saa7134_spi_gpio    spi_adap;
	struct saa7134_software_spi spi;

skip
};

/* ----------------------------------------------------------- */
/* saa7134-spi.c                                               */

int saa7134_spi_register(struct saa7134_dev *dev);
int saa7134_spi_unregister(struct saa7134_dev *dev);

saa7134-spi build to one saa7134 module. When modprobe I get NULL pointer operation.
I don't understand how to write device driver structure for store data about driver.
How to init all structure.
Must sources consist standalon SPI master driver.

With my best regards, Dmitry.

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