This patch adds basic support for spi mode 0~3 by control gpio bitbang. It uses several gpio pin and emulates spi chipselect signal, clock signal and sda signal as if spi controller generate spi signal.
Signed-off-by: Donghwa Lee <dh09.lee at samsung.com http://lists.denx.de/mailman/listinfo/u-boot>
--- drivers/spi/spi_gpio.c | 153 ++++++++++++++++++++++++++++++++++++++++++++++++ include/spi.h | 27 +++++++++ 2 files changed, 180 insertions(+), 0 deletions(-) create mode 100644 drivers/spi/spi_gpio.c
diff --git a/drivers/spi/spi_gpio.c b/drivers/spi/spi_gpio.c new file mode 100644 index 0000000..cce809e --- /dev/null +++ b/drivers/spi/spi_gpio.c @@ -0,0 +1,153 @@ +/* + * Copyright (C) 2010 Samsung Electronics + * spi_gpio.c - SPI master driver using generic bitbanged GPIO + * + * 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 + */ + + +#include <common.h> +#include <asm/arch/gpio.h> +#include <spi.h> + +static void spi_gpio_set_sck(struct spi_platform_data *spi, int is_on) +{ + gpio_set_value(spi->clk_bank, spi->clk_num, is_on); +} + +static void spi_gpio_set_mosi(struct spi_platform_data *spi, int is_on) +{ + gpio_set_value(spi->si_bank, spi->si_num, is_on); +} + +static void spi_gpio_chipselect(struct spi_platform_data *spi, + int cpol) +{ + gpio_set_value(spi->cs_bank, spi->cs_num, + !spi->cs_active); + + /* set initial clock polarity */ + if (cpol) + spi_gpio_set_sck(spi, spi->mode & SPI_CPOL); + + /* SPI is normally active-low */ + gpio_set_value(spi->cs_bank, spi->cs_num, + spi->cs_active); +} + +static void +spi_gpio_tx_cpha0(struct spi_platform_data *spi, + unsigned int nsecs, unsigned int cpol, + unsigned int word, unsigned int bits) +{ + int i; + unsigned int data; + + data = (word << spi->word_len) + bits; + + spi_gpio_chipselect(spi, cpol); + + /* clock starts at inactive polarity */ + for (i = spi->word_len; i >= 0; i--) { + + /* data high or low */ + if ((data >> i) & 0x1) + spi_gpio_set_mosi(spi, 1); + else + spi_gpio_set_mosi(spi, 0); + + udelay(nsecs); + + spi_gpio_set_sck(spi, !cpol); + udelay(nsecs); + + spi_gpio_set_sck(spi, cpol); + } +} + +static void +spi_gpio_tx_cpha1(struct spi_platform_data *spi, + unsigned int nsecs, unsigned int cpol, + unsigned int word, unsigned int bits) +{ + int i; + unsigned int data; + + data = (word << spi->word_len) + bits; + + spi_gpio_chipselect(spi, cpol); + + /* clock starts at inactive polarity */ + for (i = spi->word_len; i >= 0; i--) { + + /* setup MSB (to slave) on leading edge */ + spi_gpio_set_sck(spi, !cpol); + + /* data high or low */ + if ((data >> i) & 0x1) + spi_gpio_set_mosi(spi, 1); + else + spi_gpio_set_mosi(spi, 0); + + udelay(nsecs); + + spi_gpio_set_sck(spi, cpol); + udelay(nsecs); + } +} + +static void spi_gpio_tx_word_mode0(struct spi_platform_data *spi, + unsigned int nsecs, unsigned int word, unsigned int bits) +{ + return spi_gpio_tx_cpha0(spi, nsecs, 0, word, bits); +} + +static void spi_gpio_tx_word_mode1(struct spi_platform_data *spi, + unsigned int nsecs, unsigned int word, unsigned int bits) +{ + return spi_gpio_tx_cpha1(spi, nsecs, 0, word, bits); +} + +static void spi_gpio_tx_word_mode2(struct spi_platform_data *spi, + unsigned int nsecs, unsigned int word, unsigned int bits) +{ + return spi_gpio_tx_cpha0(spi, nsecs, 1, word, bits); +} + +static void spi_gpio_tx_word_mode3(struct spi_platform_data *spi, + unsigned int nsecs, unsigned int word, unsigned int bits) +{ + return spi_gpio_tx_cpha1(spi, nsecs, 1, word, bits); +} + +void spi_gpio_write(struct spi_platform_data *spi, + unsigned int address, unsigned int command) +{ + switch (spi->mode) { + case SPI_MODE_0: + spi_gpio_tx_word_mode0(spi, + 1, address, command); + case SPI_MODE_1: + spi_gpio_tx_word_mode1(spi, + 1, address, command); + case SPI_MODE_2: + spi_gpio_tx_word_mode2(spi, + 1, address, command); + case SPI_MODE_3: + spi_gpio_tx_word_mode3(spi, + 1, address, command); + } +} diff --git a/include/spi.h b/include/spi.h index 320e50e..ef3f94d 100644 --- a/include/spi.h +++ b/include/spi.h @@ -62,6 +62,33 @@ struct spi_slave { unsigned int cs; };
+#define COMMAND_ONLY 0xFE +#define DATA_ONLY 0xFF +#define ACTIVE_LOW 0 +#define ACTIVE_HIGH 1 + + +struct spi_platform_data { + struct s5p_gpio_bank *cs_bank; + struct s5p_gpio_bank *clk_bank; + struct s5p_gpio_bank *si_bank; + struct s5p_gpio_bank *so_bank; + + unsigned int cs_num; + unsigned int clk_num; + unsigned int si_num; + unsigned int so_num; + + unsigned int mode; + unsigned int cs_active; + unsigned int word_len; + + unsigned int set_rev; +}; + +void spi_gpio_write(struct spi_platform_data *spi, + unsigned int address, unsigned int command); + /*----------------------------------------------------------------------- * Initialization, must be called once on start up. *