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[i2c] Add a generic bit-banged i2c implementation.

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Change-Id: I3bf9b2022342e4452c525dca940ca46088b27445
Signed-off-by: John Grossman <johngro@google.com>
This commit is contained in:
John Grossman
2015-05-19 11:36:33 -07:00
parent fc44d8d651
commit 9fd7aede55
3 changed files with 355 additions and 0 deletions
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287
dev/gpio_i2c/gpio_i2c.c Normal file
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/* vim: set expandtab ts=4 sw=4 tw=100: */
/*
* Copyright (c) 2013 Google Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <assert.h>
#include <compiler.h>
#include <debug.h>
#include <printf.h>
#include <err.h>
#include <dev/gpio.h>
#include <dev/gpio_i2c.h>
#include <kernel/mutex.h>
#if (!(defined(GPIO_I2C_BUS_COUNT)) || (GPIO_I2C_BUS_COUNT <= 0))
#error ERROR: Must define GPIO_I2C_BUS_COUNT
#endif
typedef struct gpio_i2c_state {
mutex_t lock;
const gpio_i2c_info_t* info;
} gpio_i2c_state_t;
static gpio_i2c_state_t gpio_i2c_states[GPIO_I2C_BUS_COUNT];
/******************************************************************************
*
* Internal implementation.
*
******************************************************************************/
static inline void send_start(const gpio_i2c_info_t* i)
{
gpio_config(i->sda, GPIO_OUTPUT);
spin_cycles(i->qcd);
gpio_config(i->scl, GPIO_OUTPUT);
spin_cycles(i->hcd);
}
static inline void send_stop(const gpio_i2c_info_t* i)
{
gpio_config(i->sda, GPIO_OUTPUT);
gpio_config(i->scl, GPIO_INPUT);
spin_cycles(i->qcd);
gpio_config(i->sda, GPIO_INPUT);
}
static inline void send_restart(const gpio_i2c_info_t* i)
{
gpio_config(i->scl, GPIO_INPUT);
spin_cycles(i->qcd);
send_start(i);
}
static inline void send_nack(const gpio_i2c_info_t* i)
{
spin_cycles(i->hcd);
gpio_config(i->scl, GPIO_INPUT);
spin_cycles(i->hcd);
gpio_config(i->scl, GPIO_OUTPUT);
gpio_config(i->sda, GPIO_INPUT);
}
static inline void send_ack(const gpio_i2c_info_t* i)
{
gpio_config(i->sda, GPIO_OUTPUT);
send_nack(i);
}
static inline bool send_byte(const gpio_i2c_info_t* i, uint32_t b)
{
bool ret;
for (size_t j = 0; j < 8; ++j) {
if (b & 0x80)
gpio_config(i->sda, GPIO_INPUT);
else
gpio_config(i->sda, GPIO_OUTPUT);
b <<= 1;
/* setup time for data (the time between when data becomes stable and
* clock becomes a stable high) is spec'ed to be 250ns for 100KHz i2c
* and 100nsec for 400KHz i2c. If any micro running LK needs to spin
* here in order to hit that timing, they are welcome to add a spin
* right here.
*/
spin_cycles(i->hcd);
gpio_config(i->scl, GPIO_INPUT);
spin_cycles(i->hcd);
gpio_config(i->scl, GPIO_OUTPUT);
}
gpio_config(i->sda, GPIO_INPUT);
spin_cycles(i->hcd);
gpio_config(i->scl, GPIO_INPUT);
spin_cycles(i->hcd);
ret = (0 == gpio_get(i->sda));
gpio_config(i->scl, GPIO_OUTPUT);
spin_cycles(i->hcd);
return ret;
}
static inline void recv_byte(const gpio_i2c_info_t* i, uint8_t* b)
{
uint32_t tmp = 0;
for (size_t j = 0; j < 7; ++j) {
gpio_config(i->scl, GPIO_INPUT);
spin_cycles(i->hcd);
if (gpio_get(i->sda))
tmp |= 1;
tmp <<= 1;
gpio_config(i->scl, GPIO_OUTPUT);
spin_cycles(i->hcd);
}
gpio_config(i->scl, GPIO_INPUT);
spin_cycles(i->hcd);
if (gpio_get(i->sda))
tmp |= 1;
gpio_config(i->scl, GPIO_OUTPUT);
*b = (uint8_t)tmp;
}
static status_t gpio_i2c_tx_common(gpio_i2c_state_t* s,
uint8_t address,
const uint8_t* reg,
const void* buf,
size_t cnt)
{
const gpio_i2c_info_t* i = s->info;
status_t ret = ERR_I2C_NACK;
DEBUG_ASSERT(buf || !cnt);
mutex_acquire(&s->lock);
send_start(i);
if (!send_byte(i, address << 1))
goto finished;
if ((NULL != reg) && !send_byte(i, *reg))
goto finished;
for (size_t j = 0; j < cnt; ++j)
if (!send_byte(i, ((const uint8_t*)buf)[j]))
goto finished;
ret = NO_ERROR;
finished:
send_stop(i);
mutex_release(&s->lock);
return ret;
}
static status_t gpio_i2c_rx_common(gpio_i2c_state_t* s,
uint8_t address,
const uint8_t* reg,
void* buf,
size_t cnt)
{
const gpio_i2c_info_t* i = s->info;
status_t ret = ERR_I2C_NACK;
DEBUG_ASSERT(buf && cnt);
address <<= 1;
mutex_acquire(&s->lock);
send_start(i);
if (!send_byte(i, address | (!reg ? 0x1 : 0x0)))
goto finished;
if (NULL != reg) {
if (!send_byte(i, *reg))
goto finished;
send_restart(i);
if (!send_byte(i, address | 0x1))
goto finished;
}
recv_byte(i, buf++);
for (size_t j = 0; j < (cnt - 1); ++j) {
send_ack(i);
recv_byte(i, buf++);
}
send_nack(i);
ret = NO_ERROR;
finished:
send_stop(i);
mutex_release(&s->lock);
return ret;
}
void gpio_i2c_add_bus(uint32_t bus_id, const gpio_i2c_info_t* info)
{
gpio_i2c_state_t* s = gpio_i2c_states + bus_id;
DEBUG_ASSERT(info);
DEBUG_ASSERT(bus_id < GPIO_I2C_BUS_COUNT);
DEBUG_ASSERT(!s->info);
gpio_config(info->scl, GPIO_INPUT);
gpio_config(info->sda, GPIO_INPUT);
gpio_set(info->scl, 0);
gpio_set(info->sda, 0);
mutex_init(&s->lock);
s->info = info;
}
/******************************************************************************
*
* LK facing API
*
* *****************************************************************************/
void gpio_i2c_init_early(void) { }
void gpio_i2c_init(void) { }
status_t gpio_i2c_transmit(int bus, uint8_t address, const void* buf, size_t cnt)
{
gpio_i2c_state_t* s = gpio_i2c_states + bus;
if (((unsigned)bus >= countof(gpio_i2c_states)) || !s->info)
return ERR_NOT_FOUND;
return gpio_i2c_tx_common(s, address, NULL, buf, cnt);
}
status_t gpio_i2c_receive(int bus, uint8_t address, void* buf, size_t cnt)
{
gpio_i2c_state_t* s = gpio_i2c_states + bus;
if (((unsigned)bus >= countof(gpio_i2c_states)) || !s->info)
return ERR_NOT_FOUND;
return gpio_i2c_rx_common(s, address, NULL, buf, cnt);
}
status_t gpio_i2c_write_reg_bytes(int bus, uint8_t address, uint8_t reg, const uint8_t* buf, size_t cnt)
{
gpio_i2c_state_t* s = gpio_i2c_states + bus;
if (((unsigned)bus >= countof(gpio_i2c_states)) || !s->info)
return ERR_NOT_FOUND;
return gpio_i2c_tx_common(s, address, &reg, buf, cnt);
}
status_t gpio_i2c_read_reg_bytes(int bus, uint8_t address, uint8_t reg, uint8_t* buf, size_t cnt)
{
gpio_i2c_state_t* s = gpio_i2c_states + bus;
if (((unsigned)bus >= countof(gpio_i2c_states)) || !s->info) {
return ERR_NOT_FOUND;
}
return gpio_i2c_rx_common(s, address, &reg, buf, cnt);
}
void i2c_init_early(void) __WEAK_ALIAS("gpio_i2c_init_early");
void i2c_init(void) __WEAK_ALIAS("gpio_i2c_init");
status_t i2c_transmit(int, uint8_t, const void*, size_t) __WEAK_ALIAS("gpio_i2c_transmit");
status_t i2c_receive(int, uint8_t, void*, size_t) __WEAK_ALIAS("gpio_i2c_receive");
status_t i2c_write_reg_bytes(int, uint8_t, uint8_t,
const uint8_t*, size_t) __WEAK_ALIAS("gpio_i2c_write_reg_bytes");
status_t i2c_read_reg_bytes(int, uint8_t, uint8_t,
uint8_t*, size_t) __WEAK_ALIAS("gpio_i2c_read_reg_bytes");

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dev/gpio_i2c/rules.mk Normal file
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LOCAL_DIR := $(GET_LOCAL_DIR)
MODULE := $(LOCAL_DIR)
MODULE_SRCS := \
$(LOCAL_DIR)/gpio_i2c.c
MODULE_DEFINES += \
GPIO_I2C_BUS_COUNT=$(GPIO_I2C_BUS_COUNT)
include make/module.mk