[U-Boot] [PATCH] support spi gpio driver by control gpio bitbang

1 Sep 2010

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.
*
-- 
1.6.0.4


    

Donghwa Lee

Minkyu Kang

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