Add skel of i2c bitbang driver.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@1865 38d2e660-2303-0410-9eaa-f027e97ec537

diff --git a/bertos/drv/i2c_bitbang.c b/bertos/drv/i2c_bitbang.c
new file mode 100644 (file)
index 0000000..7124389
--- /dev/null
+++ b/bertos/drv/i2c_bitbang.c
@@ -0,0 +1,197 @@
+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2005 Develer S.r.l. (http://www.develer.com/)
+ *
+ * -->
+ *
+ * \brief I2C bitbang driver (implementation)
+ *
+ * \version $Id: adc.c 1604 2008-08-10 17:19:51Z bernie $
+ * \author Francesco Sacchi <batt@develer.com>
+ */
+
+#include "i2c.h"
+#include "timer.h"
+#include "hw/hw_i2c_bitbang.h"
+
+#define I2C_PERIOD DIV_ROUND(500000UL / CONFIG_I2C_FREQ)
+
+INLINE bool i2c_start(void)
+{
+       SDA_HI;
+       SCL_HI;
+       timer_udelay(I2C_PERIOD);
+       SDA_LOW;
+       timer_udelay(I2C_PERIOD);
+       return !SDA;
+}
+
+INLINE void i2c_stop(void)
+{
+       SCL_HI;
+       timer_udelay(I2C_PERIOD);
+       SDA_HI;
+}
+
+bool i2c_put(uint8_t _data)
+{
+       uint16_t data = (_data << 1) | 1;
+       for (uint16_t i = 0x100; i >= 0; i >>= 1)
+       {
+               SCL_LO;
+               timer_udelay(I2C_PERIOD);
+               if (data & i)
+                       SDA_HI;
+               else
+                       SDA_LO;
+               SCL_HI;
+               timer_udelay(I2C_PERIOD);
+               ASSERT(SDA == (data & i));
+       }
+       bool ack = !SDA;
+       ASSERT(ack);
+       SCL_LO;
+       timer_udelay(I2C_PERIOD);
+       return ack;
+}
+
+bool i2c_start_w(uint8_t id)
+{
+       id &= ~I2C_READBIT;
+       /*
+        * Loop on the select write sequence: when the device is busy
+        * writing previously sent data it will reply to the SLA_W
+        * control byte with a NACK.  In this case, we must
+        * keep trying until the deveice responds with an ACK.
+        */
+       ticks_t start = timer_clock();
+       while (i2c_start())
+       {
+               if (i2c_put(id))
+                       return true;
+               else if (timer_clock() - start > ms_to_ticks(CONFIG_TWI_START_TIMEOUT))
+               {
+                       LOG_ERR("Timeout on I2C start write\n");
+                       break;
+               }
+       }
+
+       return false;
+}
+
+bool i2c_start_r(uint8_t id)
+{
+       id |= I2C_READBIT;
+       if (i2c_start())
+       {
+               if (i2c_put(id))
+                       return true;
+
+               LOG_ERR("NACK on I2c start read\n");
+       }
+
+       return false;
+}
+
+int i2c_get(bool ack)
+{
+       uint8_t data = 0;
+       for (uint8_t i = 0x80; i >= 0; i >>= 1)
+       {
+               SCL_LO;
+               timer_udelay(I2C_PERIOD);
+               SCL_HI;
+               timer_udelay(I2C_PERIOD);
+               if (SDA)
+                       data |= i;
+       }
+       SCL_LO;
+       timer_udelay(I2C_PERIOD);
+
+       if (ack)
+               SDA_LO;
+       else
+               SDA_HI;
+
+       SCL_HI;
+       /* avoid sign extension */
+       return (int)(uint8_t)data;
+}
+
+/**
+ * Send a sequence of bytes in master transmitter mode
+ * to the selected slave device through the I2C bus.
+ *
+ * \return true on success, false on error.
+ */
+bool i2c_send(const void *_buf, size_t count)
+{
+       const uint8_t *buf = (const uint8_t *)_buf;
+
+       while (count--)
+       {
+               if (!i2c_put(*buf++))
+                       return false;
+       }
+       return true;
+}
+
+/**
+ * Receive a sequence of one or more bytes from the
+ * selected slave device in master receive mode through
+ * the I2C bus.
+ *
+ * Received data is placed in \c buf.
+ *
+ * \note a NACK is automatically given on the last received
+ *         byte.
+ *
+ * \return true on success, false on error
+ */
+bool i2c_recv(void *_buf, size_t count)
+{
+       uint8_t *buf = (uint8_t *)_buf;
+
+       while (count--)
+       {
+               /*
+                * The last byte read does not has an ACK
+                * to stop communication.
+                */
+               int c = i2c_get(count);
+
+               if (c == EOF)
+                       return false;
+               else
+                       *buf++ = c;
+       }
+
+       return true;
+}
+