254 lines
6.2 KiB
C
254 lines
6.2 KiB
C
/**
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* \file
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* <!--
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* This file is part of BeRTOS.
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*
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* Bertos is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* As a special exception, you may use this file as part of a free software
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* library without restriction. Specifically, if other files instantiate
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* templates or use macros or inline functions from this file, or you compile
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* this file and link it with other files to produce an executable, this
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* file does not by itself cause the resulting executable to be covered by
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* the GNU General Public License. This exception does not however
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* invalidate any other reasons why the executable file might be covered by
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* the GNU General Public License.
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*
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* Copyright 2011 Develer S.r.l. (http://www.develer.com/)
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*
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* -->
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*
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* \brief TWI driver for SAM3 (implementation)
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*
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* Only master mode is supported.
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*
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* \author Stefano Fedrigo <aleph@develer.com>
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*/
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#include "cfg/cfg_i2c.h"
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#define LOG_LEVEL I2C_LOG_LEVEL
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#define LOG_FORMAT I2C_LOG_FORMAT
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#include <cfg/log.h>
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#include <hw/hw_cpufreq.h> // CPU_FREQ
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#include <cfg/debug.h>
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#include <cfg/macros.h> // BV()
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#include <cfg/module.h>
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#include <cpu/detect.h>
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#include <cpu/irq.h>
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#include <cpu/power.h>
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#include <drv/timer.h>
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#include <drv/i2c.h>
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#include <io/sam3.h>
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struct I2cHardware
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{
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uint32_t base;
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bool first_xtranf;
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};
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INLINE bool waitTxRdy(I2c *i2c, time_t ms_timeout)
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{
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ticks_t start = timer_clock();
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while (!(HWREG(i2c->hw->base + TWI_SR_OFF) & TWI_SR_TXRDY))
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{
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if (timer_clock() - start > ms_to_ticks(ms_timeout))
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return false;
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cpu_relax();
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}
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return true;
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}
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INLINE bool waitRxRdy(I2c *i2c, time_t ms_timeout)
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{
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ticks_t start = timer_clock();
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while (!(HWREG(i2c->hw->base + TWI_SR_OFF) & TWI_SR_RXRDY))
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{
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if (timer_clock() - start > ms_to_ticks(ms_timeout))
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return false;
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cpu_relax();
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}
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return true;
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}
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INLINE void waitXferComplete(I2c *i2c)
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{
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while (!(HWREG(i2c->hw->base + TWI_SR_OFF) & TWI_SR_TXCOMP))
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cpu_relax();
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}
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/*
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* The start is not performed when we call the start function
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* because the hardware should know the first data byte to send.
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* Generally to perform a byte send we should write the slave address
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* in slave address register and the first byte to send in data registry.
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* After then we can perform the start write procedure, and send really
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* the our data. To use common bertos i2c api the really start will be
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* performed when the user "put" or "send" its data. These tricks are hide
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* from the driver implementation.
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*/
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static void i2c_sam3_start(struct I2c *i2c, uint16_t slave_addr)
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{
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i2c->hw->first_xtranf = true;
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if (I2C_TEST_START(i2c->flags) == I2C_START_R)
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HWREG(i2c->hw->base + TWI_MMR_OFF) = TWI_MMR_DADR(slave_addr >> 1) | TWI_MMR_MREAD;
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else
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HWREG(i2c->hw->base + TWI_MMR_OFF) = TWI_MMR_DADR(slave_addr >> 1);
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}
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static void i2c_sam3_putc(I2c *i2c, const uint8_t data)
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{
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if (!waitTxRdy(i2c, CONFIG_I2C_START_TIMEOUT))
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{
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LOG_ERR("i2c: txready timeout\n");
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i2c->errors |= I2C_START_TIMEOUT;
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return;
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}
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HWREG(i2c->hw->base + TWI_THR_OFF) = data;
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if ((i2c->xfer_size == 1) && (I2C_TEST_STOP(i2c->flags) == I2C_STOP))
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HWREG(i2c->hw->base + TWI_CR_OFF) = TWI_CR_STOP;
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// On first byte sent wait for start timeout
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if (i2c->hw->first_xtranf && !waitTxRdy(i2c, CONFIG_I2C_START_TIMEOUT))
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{
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LOG_ERR("i2c: write start timeout\n");
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i2c->errors |= I2C_START_TIMEOUT;
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HWREG(i2c->hw->base + TWI_CR_OFF) = TWI_CR_STOP;
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waitXferComplete(i2c);
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return;
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}
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i2c->hw->first_xtranf = false;
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if ((i2c->xfer_size == 1) && (I2C_TEST_STOP(i2c->flags) == I2C_STOP))
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waitXferComplete(i2c);
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}
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static uint8_t i2c_sam3_getc(I2c *i2c)
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{
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uint8_t data;
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uint32_t cr = 0;
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if (i2c->hw->first_xtranf)
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{
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cr |= TWI_CR_START;
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i2c->hw->first_xtranf = false;
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}
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if ((i2c->xfer_size == 1) && (I2C_TEST_STOP(i2c->flags) == I2C_STOP))
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cr |= TWI_CR_STOP;
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HWREG(i2c->hw->base + TWI_CR_OFF) = cr;
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if (!waitRxRdy(i2c, CONFIG_I2C_START_TIMEOUT))
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{
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LOG_ERR("i2c: read start timeout\n");
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i2c->errors |= I2C_START_TIMEOUT;
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return 0xFF;
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}
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data = HWREG(i2c->hw->base + TWI_RHR_OFF);
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if ((i2c->xfer_size == 1) && (I2C_TEST_STOP(i2c->flags) == I2C_STOP))
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waitXferComplete(i2c);
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return data;
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}
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static void i2c_setClock(I2c *i2c, int clock)
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{
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uint32_t ck_div = 0;
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uint32_t cl_div;
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for (;;)
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{
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cl_div = ((CPU_FREQ / (2 * clock)) - 4) / (1 << ck_div);
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if (cl_div <= 255)
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break;
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ck_div++;
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}
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ASSERT(ck_div < 8);
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LOG_INFO("i2c: using CKDIV = %lu and CLDIV/CHDIV = %lu\n\n", ck_div, cl_div);
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HWREG(i2c->hw->base + TWI_CWGR_OFF) = 0;
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HWREG(i2c->hw->base + TWI_CWGR_OFF) = (ck_div << 16) | (cl_div << 8) | cl_div;
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}
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static const I2cVT i2c_sam3_vt =
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{
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.start = i2c_sam3_start,
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.getc = i2c_sam3_getc,
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.putc = i2c_sam3_putc,
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.write = i2c_genericWrite,
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.read = i2c_genericRead,
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};
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struct I2cHardware i2c_sam3_hw[I2C_CNT];
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/**
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* Initialize I2C module.
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*/
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void i2c_hw_init(I2c *i2c, int dev, uint32_t clock)
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{
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ASSERT(dev < I2C_CNT);
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i2c->hw = &i2c_sam3_hw[dev];
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i2c->vt = &i2c_sam3_vt;
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pmc_periphEnable(PIOA_ID);
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switch (dev)
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{
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case I2C0:
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i2c->hw->base = TWI0_BASE;
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PIO_PERIPH_SEL(TWI0_PORT, BV(TWI0_TWD) | BV(TWI0_TWCK), TWI0_PERIPH);
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HWREG(TWI0_PORT + PIO_PDR_OFF) = BV(TWI0_TWD) | BV(TWI0_TWCK);
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pmc_periphEnable(TWI0_ID);
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break;
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case I2C1:
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i2c->hw->base = TWI1_BASE;
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PIO_PERIPH_SEL(TWI1_PORT, BV(TWI1_TWD) | BV(TWI1_TWCK), TWI1_PERIPH);
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HWREG(TWI1_PORT + PIO_PDR_OFF) = BV(TWI1_TWD) | BV(TWI1_TWCK);
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pmc_periphEnable(TWI1_ID);
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break;
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default:
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ASSERT(!"i2c: invalid dev number");
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return;
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}
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// Reset and set master mode
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HWREG(i2c->hw->base + TWI_CR_OFF) = TWI_CR_SWRST;
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HWREG(i2c->hw->base + TWI_CR_OFF) = TWI_CR_MSEN | TWI_CR_SVDIS;
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i2c_setClock(i2c, clock);
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}
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