[RFC] spi: add demo bitbang driver based on code from linux
Jean-Christophe PLAGNIOL-VILLARD
plagnioj at jcrosoft.com
Thu Sep 6 05:09:38 EDT 2012
On 11:53 Thu 06 Sep , Antony Pavlov wrote:
> It not the real driver but demonstration of the conception.
> The code was tested on real hardware, but the code for
> this hardware can't be published just now.
>
> Usage of bitbang framework is very easy.
> You must declare the functions for setting CLK and MOSI signals,
> and the function for reading MISO signal:
>
> * void setsck(struct spi_device *, int is_on);
> * void setmosi(struct spi_device *, int is_on);
> * int getmiso(struct spi_device *);
>
> Next include the "spi-bitbang-txrx.h" header. The header
> will give you the functions for reading/writing u32 words from/to spi.
>
> Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
can you implement the gpio driver base on it
so we can test it and ack it
and does this work owith mmc-spi?
Best Regards,
J.
> ---
> arch/mips/boards/qemu-malta/init.c | 31 +++++++
> drivers/spi/Kconfig | 4 +
> drivers/spi/Makefile | 1 +
> drivers/spi/bitbang_demo_spi.c | 176 ++++++++++++++++++++++++++++++++++++
> drivers/spi/spi-bitbang-txrx.h | 93 +++++++++++++++++++
> 5 files changed, 305 insertions(+)
> create mode 100644 drivers/spi/bitbang_demo_spi.c
> create mode 100644 drivers/spi/spi-bitbang-txrx.h
>
> diff --git a/arch/mips/boards/qemu-malta/init.c b/arch/mips/boards/qemu-malta/init.c
> index 45f66f2..314ca88 100644
> --- a/arch/mips/boards/qemu-malta/init.c
> +++ b/arch/mips/boards/qemu-malta/init.c
> @@ -30,6 +30,8 @@
> #include <partition.h>
> #include <sizes.h>
> #include <asm/common.h>
> +#include <spi/spi.h>
> +#include <spi/flash.h>
>
> static int malta_mem_init(void)
> {
> @@ -64,3 +66,32 @@ static int malta_console_init(void)
> return 0;
> }
> console_initcall(malta_console_init);
> +
> +static struct flash_platform_data malta_spi_demo_flash_data = {
> + .name = "spi",
> + .type = "s25sl004a",
> +};
> +
> +static struct spi_board_info malta_spi_demo_devs[] __initdata = {
> + {
> + /* Spansion S25FL004A SPI flash */
> + .name = "m25p",
> + .max_speed_hz = 50000000,
> + .bus_num = 0,
> + .chip_select = 0,
> + .mode = SPI_MODE_3,
> + .platform_data = &malta_spi_demo_flash_data,
> + },
> +};
> +
> +static int malta_spi_demo_init(void)
> +{
> +
> + spi_register_board_info(malta_spi_demo_devs,
> + ARRAY_SIZE(malta_spi_demo_devs));
> + add_generic_device("bitbang_demo_spi", -1, NULL,
> + 0, 0, IORESOURCE_MEM, NULL);
> +
> + return 0;
> +}
> +device_initcall(malta_spi_demo_init);
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index b5c55a4..d883cd4 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -34,4 +34,8 @@ config DRIVER_SPI_ATMEL
> depends on ARCH_AT91
> depends on SPI
>
> +config DRIVER_SPI_BITBANG_DEMO
> + bool "BITBANG DEMO SPI controller"
> + depends on SPI
> +
> endmenu
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index 101652f..087a982 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -2,3 +2,4 @@ obj-$(CONFIG_SPI) += spi.o
> obj-$(CONFIG_DRIVER_SPI_IMX) += imx_spi.o
> obj-$(CONFIG_DRIVER_SPI_ALTERA) += altera_spi.o
> obj-$(CONFIG_DRIVER_SPI_ATMEL) += atmel_spi.o
> +obj-$(CONFIG_DRIVER_SPI_BITBANG_DEMO) += bitbang_demo_spi.o
> diff --git a/drivers/spi/bitbang_demo_spi.c b/drivers/spi/bitbang_demo_spi.c
> new file mode 100644
> index 0000000..76abf98
> --- /dev/null
> +++ b/drivers/spi/bitbang_demo_spi.c
> @@ -0,0 +1,176 @@
> +/*
> + * Copyright (C) 2012 Antony Pavlov <antonynpavlov at gmail.com>
> + *
> + * This file is part of barebox.
> + * See file CREDITS for list of people who contributed to this project.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> + * MA 02111-1307 USA
> + *
> + */
> +
> +#define DEBUG
> +
> +#include <common.h>
> +#include <init.h>
> +#include <driver.h>
> +#include <spi/spi.h>
> +#include <io.h>
> +#include <clock.h>
> +
> +struct spi_bitbang_demo_master {
> + int num_chipselect;
> + int spi_mode;
> + int databits;
> + int speed;
> + int bus_num;
> +};
> +
> +struct bitbang_demo_spi {
> + struct spi_master master;
> + int databits;
> + int speed;
> + int mode;
> +};
> +
> +static inline void setsck(struct spi_device *spi, int on)
> +{
> + struct bitbang_demo_spi *sc = container_of(spi->master, struct bitbang_demo_spi, master);
> +
> + /* do something ... */
> + (void)sc;
> +}
> +
> +static inline void setmosi(struct spi_device *spi, int on)
> +{
> + struct bitbang_demo_spi *sc = container_of(spi->master, struct bitbang_demo_spi, master);
> +
> + /* do something ... */
> + (void)sc;
> +}
> +
> +static inline u32 getmiso(struct spi_device *spi)
> +{
> + struct bitbang_demo_spi *sc = container_of(spi->master, struct bitbang_demo_spi, master);
> +
> + /* do something ... */
> + (void)sc;
> +
> + return 0;
> +}
> +
> +#include "spi-bitbang-txrx.h"
> +
> +static int bitbang_demo_spi_setup(struct spi_device *spi)
> +{
> + struct spi_master *master = spi->master;
> + struct bitbang_demo_spi *sc = container_of(master, struct bitbang_demo_spi, master);
> +
> + dev_dbg(master->dev, "%s\n", __func__);
> + printf("%s chipsel %d mode 0x%08x bits_per_word: %d speed: %d\n",
> + __FUNCTION__, spi->chip_select, spi->mode, spi->bits_per_word,
> + spi->max_speed_hz);
> +
> + /* do something ... */
> + (void) sc;
> +
> + return 0;
> +}
> +
> +static int bitbang_demo_read(struct spi_device *spi, void *buf, size_t nbyte)
> +{
> + ssize_t cnt = 0;
> + volatile u8 *rxf_buf = buf;
> +
> + /* SPI_MODE_3 only */
> + while (cnt < nbyte) {
> + *rxf_buf = bitbang_txrx_be_cpha1(spi, 1000, 1, 0, 8);
> + rxf_buf++;
> + cnt++;
> + }
> +
> + return cnt;
> +}
> +
> +static int bitbang_demo_write(struct spi_device *spi, const void *buf, size_t nbyte)
> +{
> + ssize_t cnt = 0;
> + const u8 *txf_buf = buf;
> +
> + /* SPI_MODE_3 only */
> + while (cnt < nbyte) {
> + bitbang_txrx_be_cpha1(spi, 1000, 1, (u32)*txf_buf, 8);
> + txf_buf++;
> + cnt++;
> + }
> +
> + return 0;
> +}
> +
> +static int bitbang_demo_spi_transfer(struct spi_device *spi, struct spi_message *mesg)
> +{
> + struct spi_master *master = spi->master;
> + struct spi_transfer *t;
> +
> + dev_dbg(master->dev, "%s\n", __func__);
> +
> + mesg->actual_length = 0;
> +
> + /* chip select and mode select stuff skipped */
> +
> + list_for_each_entry(t, &mesg->transfers, transfer_list) {
> +
> + if (t->tx_buf)
> + bitbang_demo_write(spi, t->tx_buf, t->len);
> +
> + if (t->rx_buf)
> + bitbang_demo_read(spi, t->rx_buf, t->len);
> +
> + mesg->actual_length += t->len;
> + }
> +
> + return 0;
> +}
> +
> +static int bitbang_demo_spi_probe(struct device_d *dev)
> +{
> + struct spi_master *master;
> + struct bitbang_demo_spi *bitbang_demo_spi;
> +
> + bitbang_demo_spi = xzalloc(sizeof(*bitbang_demo_spi));
> +
> + master = &bitbang_demo_spi->master;
> + master->dev = dev;
> +
> + master->setup = bitbang_demo_spi_setup;
> + master->transfer = bitbang_demo_spi_transfer;
> + master->num_chipselect = 1;
> + master->bus_num = 0;
> +
> + spi_register_master(master);
> +
> + return 0;
> +}
> +
> +static struct driver_d bitbang_demo_spi_driver = {
> + .name = "bitbang_demo_spi",
> + .probe = bitbang_demo_spi_probe,
> +};
> +
> +static int bitbang_demo_spi_driver_init(void)
> +{
> + return register_driver(&bitbang_demo_spi_driver);
> +}
> +device_initcall(bitbang_demo_spi_driver_init);
> diff --git a/drivers/spi/spi-bitbang-txrx.h b/drivers/spi/spi-bitbang-txrx.h
> new file mode 100644
> index 0000000..e86eec2
> --- /dev/null
> +++ b/drivers/spi/spi-bitbang-txrx.h
> @@ -0,0 +1,93 @@
> +/*
> + * Mix this utility code with some glue code to get one of several types of
> + * simple SPI master driver. Two do polled word-at-a-time I/O:
> + *
> + * - GPIO/parport bitbangers. Provide chipselect() and txrx_word[](),
> + * expanding the per-word routines from the inline templates below.
> + *
> + * - Drivers for controllers resembling bare shift registers. Provide
> + * chipselect() and txrx_word[](), with custom setup()/cleanup() methods
> + * that use your controller's clock and chipselect registers.
> + *
> + * Some hardware works well with requests at spi_transfer scope:
> + *
> + * - Drivers leveraging smarter hardware, with fifos or DMA; or for half
> + * duplex (MicroWire) controllers. Provide chipselect() and txrx_bufs(),
> + * and custom setup()/cleanup() methods.
> + */
> +
> +/*
> + * The code that knows what GPIO pins do what should have declared four
> + * functions, ideally as inlines, before including this header:
> + *
> + * void setsck(struct spi_device *, int is_on);
> + * void setmosi(struct spi_device *, int is_on);
> + * int getmiso(struct spi_device *);
> + * void spidelay(unsigned);
> + *
> + * setsck()'s is_on parameter is a zero/nonzero boolean.
> + *
> + * setmosi()'s is_on parameter is a zero/nonzero boolean.
> + *
> + * getmiso() is required to return 0 or 1 only. Any other value is invalid
> + * and will result in improper operation.
> + *
> + * A non-inlined routine would call bitbang_txrx_*() routines. The
> + * main loop could easily compile down to a handful of instructions,
> + * especially if the delay is a NOP (to run at peak speed).
> + *
> + * Since this is software, the timings may not be exactly what your board's
> + * chips need ... there may be several reasons you'd need to tweak timings
> + * in these routines, not just make to make it faster or slower to match a
> + * particular CPU clock rate.
> + */
> +
> +#define spidelay(nsecs) udelay(nsecs/1000)
> +
> +static inline u32
> +bitbang_txrx_be_cpha0(struct spi_device *spi,
> + unsigned nsecs, unsigned cpol, u32 word, u8 bits)
> +{
> + /* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */
> +
> + /* clock starts at inactive polarity */
> + for (word <<= (32 - bits); likely(bits); bits--) {
> +
> + /* setup MSB (to slave) on trailing edge */
> + setmosi(spi, word & (1 << 31));
> + spidelay(nsecs); /* T(setup) */
> +
> + setsck(spi, !cpol);
> + spidelay(nsecs);
> +
> + /* sample MSB (from slave) on leading edge */
> + word <<= 1;
> + word |= getmiso(spi);
> + setsck(spi, cpol);
> + }
> + return word;
> +}
> +
> +static inline u32
> +bitbang_txrx_be_cpha1(struct spi_device *spi, unsigned nsecs, unsigned cpol,
> + u32 word, u8 bits)
> +{
> + /* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */
> +
> + /* clock starts at inactive polarity */
> + for (word <<= (32 - bits); likely(bits); bits--) {
> +
> + /* setup MSB (to slave) on leading edge */
> + setsck(spi, !cpol);
> + setmosi(spi, word & (1 << 31));
> + spidelay(nsecs); /* T(setup) */
> +
> + setsck(spi, cpol);
> + spidelay(nsecs);
> +
> + /* sample MSB (from slave) on trailing edge */
> + word <<= 1;
> + word |= getmiso(spi);
> + }
> + return word;
> +}
> --
> 1.7.10.4
>
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