7fb0f71668
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@13720 a1c6a512-1295-4272-9138-f99709370657
125 lines
3.7 KiB
C
125 lines
3.7 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2007 by Michael Sevakis
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*
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* All files in this archive are subject to the GNU General Public License.
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* See the file COPYING in the source tree root for full license agreement.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "system.h"
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#include "i2c-meg-fx.h"
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/* Only implements sending bytes for now. Adding receiving bytes should be
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straightforward if needed. No yielding is present since the calls only
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involve setting audio codec registers - a very rare event. */
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/* Wait for a condition on the bus, optionally returning it */
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#define COND_RET _c;
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#define COND_VOID
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#define WAIT_COND(cond, ret) \
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({ \
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int _t = current_tick + 2; \
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bool _c; \
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while (1) { \
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_c = !!(cond); \
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if (_c || TIME_AFTER(current_tick, _t)) \
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break; \
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} \
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ret \
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})
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static int i2c_getack(void)
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{
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/* Wait for ACK: 0 = ack received, 1 = ack not received */
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WAIT_COND(IICCON & I2C_TXRX_INTPND, COND_VOID);
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return IICSTAT & I2C_ACK_L;
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}
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static int i2c_start(void)
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{
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/* Generate START */
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IICSTAT = I2C_MODE_MASTER | I2C_MODE_TX | I2C_START | I2C_RXTX_ENB;
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return i2c_getack();
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}
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static void i2c_stop(void)
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{
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/* Generate STOP */
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IICSTAT = I2C_MODE_MASTER | I2C_MODE_TX | I2C_RXTX_ENB;
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/* Clear pending interrupt to continue */
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IICCON &= ~I2C_TXRX_INTPND;
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}
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static int i2c_outb(unsigned char byte)
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{
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/* Write byte to shift register */
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IICDS = byte;
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/* Clear pending interrupt to continue */
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IICCON &= ~I2C_TXRX_INTPND;
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return i2c_getack();
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}
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void i2c_write(int addr, const unsigned char *buf, int count)
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{
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/* Turn on I2C clock */
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CLKCON |= (1 << 16);
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/* Set mode to master transmitter and enable lines */
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IICSTAT = I2C_MODE_MASTER | I2C_MODE_TX | I2C_RXTX_ENB;
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/* Wait for bus to be available */
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if (WAIT_COND(!(IICSTAT & I2C_BUSY), COND_RET))
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{
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/* Send slave address and then data */
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IICCON &= ~I2C_TXRX_INTPND;
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IICCON |= I2C_TXRX_INTENB;
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IICDS = addr & 0xfe;
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if (i2c_start() == 0)
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while (count-- > 0 && i2c_outb(*buf++) == 0);
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i2c_stop();
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IICCON &= ~I2C_TXRX_INTENB;
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}
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/* Go back to slave receive mode and disable lines */
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IICSTAT = 0;
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/* Turn off I2C clock */
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CLKCON &= ~(1 << 16);
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}
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void i2c_init(void)
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{
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/* We poll I2C interrupts */
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INTMSK |= (1 << 27);
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/* Turn on I2C clock */
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CLKCON |= (1 << 16);
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/* Set GPE15 (IICSDA) and GPE14 (IICSCL) to IIC */
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GPECON = (GPECON & ~((3 << 30) | (3 << 28))) |
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((2 << 30) | (2 << 28));
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/* Bus ACK, IICCLK: fPCLK / 16, Rx/Tx Int: Disable, Tx clock: IICCLK/8 */
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/* OF PCLK: 49.1568MHz / 16 / 8 = 384.0375 kHz */
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IICCON = (7 << 0);
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/* SDA line delayed 0 PCLKs */
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IICLC = (0 << 0);
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/* Turn off I2C clock */
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CLKCON &= ~(1 << 16);
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}
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