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/*
* Copyright (c) 2016 Piotr Mienkowski
* SPDX-License-Identifier: Apache-2.0
*/
/** @file
* @brief USART driver for Atmel SAM MCU family.
*
* Note:
* - Only basic USART features sufficient to support printf functionality
* are currently implemented.
* - The driver works only in polling mode, interrupt mode is not implemented.
*/
#include <errno.h>
#include <misc/__assert.h>
#include <device.h>
#include <init.h>
#include <soc.h>
#include <uart.h>
/*
* Verify Kconfig configuration
*/
#if CONFIG_USART_SAM_PORT_0 == 1
#if CONFIG_USART_SAM_PORT_0_BAUD_RATE == 0
#error "CONFIG_USART_SAM_PORT_0_BAUD_RATE has to be bigger than 0"
#endif
#endif
#if CONFIG_USART_SAM_PORT_1 == 1
#if CONFIG_USART_SAM_PORT_1_BAUD_RATE == 0
#error "CONFIG_USART_SAM_PORT_1_BAUD_RATE has to be bigger than 0"
#endif
#endif
#if CONFIG_USART_SAM_PORT_2 == 1
#if CONFIG_USART_SAM_PORT_2_BAUD_RATE == 0
#error "CONFIG_USART_SAM_PORT_2_BAUD_RATE has to be bigger than 0"
#endif
#endif
/* Device constant configuration parameters */
struct usart_sam_dev_cfg {
Usart *regs;
uint32_t periph_id;
struct soc_gpio_pin pin_rx;
struct soc_gpio_pin pin_tx;
};
/* Device run time data */
struct usart_sam_dev_data {
uint32_t baud_rate;
};
#define DEV_CFG(dev) \
((const struct usart_sam_dev_cfg *const)(dev)->config->config_info)
#define DEV_DATA(dev) \
((struct usart_sam_dev_data *const)(dev)->driver_data)
static int baudrate_set(Usart *const usart, uint32_t baudrate,
uint32_t mck_freq_hz);
static int usart_sam_init(struct device *dev)
{
int retval;
const struct usart_sam_dev_cfg *const cfg = DEV_CFG(dev);
struct usart_sam_dev_data *const dev_data = DEV_DATA(dev);
Usart *const usart = cfg->regs;
/* Enable USART clock in PMC */
soc_pmc_peripheral_enable(cfg->periph_id);
/* Connect pins to the peripheral */
soc_gpio_configure(&cfg->pin_rx);
soc_gpio_configure(&cfg->pin_tx);
/* Reset and disable USART */
usart->US_CR = US_CR_RSTRX | US_CR_RSTTX
| US_CR_RXDIS | US_CR_TXDIS | US_CR_RSTSTA;
/* Disable Interrupts */
usart->US_IDR = 0xFFFFFFFF;
/* 8 bits of data, no parity, 1 stop bit in normal mode */
usart->US_MR = US_MR_NBSTOP_1_BIT
| US_MR_PAR_NO
| US_MR_CHRL_8_BIT
| US_MR_USCLKS_MCK
| US_MR_CHMODE_NORMAL;
/* Set baud rate */
retval = baudrate_set(usart, dev_data->baud_rate,
SOC_ATMEL_SAM_MCK_FREQ_HZ);
if (retval != 0) {
return retval;
};
/* Enable receiver and transmitter */
usart->US_CR = US_CR_RXEN | US_CR_TXEN;
return 0;
}
static int usart_sam_poll_in(struct device *dev, unsigned char *c)
{
Usart *const usart = DEV_CFG(dev)->regs;
if (!(usart->US_CSR & US_CSR_RXRDY)) {
return -EBUSY;
}
/* got a character */
*c = (unsigned char)usart->US_RHR;
return 0;
}
static unsigned char usart_sam_poll_out(struct device *dev, unsigned char c)
{
Usart *const usart = DEV_CFG(dev)->regs;
/* Wait for transmitter to be ready */
while (!(usart->US_CSR & US_CSR_TXRDY))
;
/* send a character */
usart->US_THR = (uint32_t)c;
return c;
}
static int baudrate_set(Usart *const usart, uint32_t baudrate,
uint32_t mck_freq_hz)
{
uint32_t divisor;
__ASSERT(baudrate,
"baud rate has to be bigger than 0");
__ASSERT(mck_freq_hz/16 >= baudrate,
"MCK frequency is too small to set required baud rate");
divisor = mck_freq_hz / 16 / baudrate;
if (divisor > 0xFFFF) {
return -EINVAL;
};
usart->US_BRGR = US_BRGR_CD(divisor);
return 0;
}
static const struct uart_driver_api usart_sam_driver_api = {
.poll_in = usart_sam_poll_in,
.poll_out = usart_sam_poll_out,
};
/* USART0 */
#ifdef CONFIG_USART_SAM_PORT_0
static const struct usart_sam_dev_cfg usart0_sam_config = {
.regs = USART0,
.periph_id = ID_USART0,
.pin_rx = PIN_USART0_RXD,
.pin_tx = PIN_USART0_TXD,
};
static struct usart_sam_dev_data usart0_sam_data = {
.baud_rate = CONFIG_USART_SAM_PORT_0_BAUD_RATE,
};
DEVICE_AND_API_INIT(usart0_sam, CONFIG_USART_SAM_PORT_0_NAME, &usart_sam_init,
&usart0_sam_data, &usart0_sam_config, PRE_KERNEL_1,
CONFIG_KERNEL_INIT_PRIORITY_DEVICE, &usart_sam_driver_api);
#endif
/* USART1 */
#ifdef CONFIG_USART_SAM_PORT_1
static const struct usart_sam_dev_cfg usart1_sam_config = {
.regs = USART1,
.periph_id = ID_USART1,
.pin_rx = PIN_USART1_RXD,
.pin_tx = PIN_USART1_TXD,
};
static struct usart_sam_dev_data usart1_sam_data = {
.baud_rate = CONFIG_USART_SAM_PORT_1_BAUD_RATE,
};
DEVICE_AND_API_INIT(usart1_sam, CONFIG_USART_SAM_PORT_1_NAME, &usart_sam_init,
&usart1_sam_data, &usart1_sam_config, PRE_KERNEL_1,
CONFIG_KERNEL_INIT_PRIORITY_DEVICE, &usart_sam_driver_api);
#endif
/* USART2 */
#ifdef CONFIG_USART_SAM_PORT_2
static const struct usart_sam_dev_cfg usart2_sam_config = {
.regs = USART2,
.periph_id = ID_USART2,
.pin_rx = PIN_USART2_RXD,
.pin_tx = PIN_USART2_TXD,
};
static struct usart_sam_dev_data usart2_sam_data = {
.baud_rate = CONFIG_USART_SAM_PORT_2_BAUD_RATE,
};
DEVICE_AND_API_INIT(usart2_sam, CONFIG_USART_SAM_PORT_2_NAME, &usart_sam_init,
&usart2_sam_data, &usart2_sam_config, PRE_KERNEL_1,
CONFIG_KERNEL_INIT_PRIORITY_DEVICE, &usart_sam_driver_api);
#endif