355 lines
9.2 KiB
C
355 lines
9.2 KiB
C
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/*
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* Copyright (c) 2019-2020 Cobham Gaisler AB
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#define DT_DRV_COMPAT gaisler_apbuart
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#include <drivers/uart.h>
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#include <errno.h>
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/* APBUART registers
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*
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* Offset | Name | Description
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* ------ | ------ | ----------------------------------------
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* 0x0000 | data | UART data register
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* 0x0004 | status | UART status register
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* 0x0008 | ctrl | UART control register
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* 0x000c | scaler | UART scaler register
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* 0x0010 | debug | UART FIFO debug register
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*/
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struct apbuart_regs {
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/** @brief UART data register
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*
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* Bit | Name | Description
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* ------ | ------ | ----------------------------------------
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* 7-0 | data | Holding register or FIFO
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*/
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uint32_t data; /* 0x0000 */
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/** @brief UART status register
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*
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* Bit | Name | Description
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* ------ | ------ | ----------------------------------------
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* 31-26 | RCNT | Receiver FIFO count
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* 25-20 | TCNT | Transmitter FIFO count
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* 10 | RF | Receiver FIFO full
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* 9 | TF | Transmitter FIFO full
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* 8 | RH | Receiver FIFO half-full
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* 7 | TH | Transmitter FIFO half-full
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* 6 | FE | Framing error
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* 5 | PE | Parity error
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* 4 | OV | Overrun
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* 3 | BR | Break received
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* 2 | TE | Transmitter FIFO empty
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* 1 | TS | Transmitter shift register empty
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* 0 | DR | Data ready
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*/
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uint32_t status; /* 0x0004 */
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/** @brief UART control register
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*
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* Bit | Name | Description
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* ------ | ------ | ----------------------------------------
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* 31 | FA | FIFOs available
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* 14 | SI | Transmitter shift register empty interrupt enable
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* 13 | DI | Delayed interrupt enable
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* 12 | BI | Break interrupt enable
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* 11 | DB | FIFO debug mode enable
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* 10 | RF | Receiver FIFO interrupt enable
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* 9 | TF | Transmitter FIFO interrupt enable
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* 8 | EC | External clock
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* 7 | LB | Loop back
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* 6 | FL | Flow control
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* 5 | PE | Parity enable
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* 4 | PS | Parity select
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* 3 | TI | Transmitter interrupt enable
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* 2 | RI | Receiver interrupt enable
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* 1 | TE | Transmitter enable
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* 0 | RE | Receiver enable
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*/
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uint32_t ctrl; /* 0x0008 */
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/** @brief UART scaler register
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*
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* Bit | Name | Description
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* ------ | ------ | ----------------------------------------
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* 11-0 | RELOAD | Scaler reload value
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*/
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uint32_t scaler; /* 0x000c */
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/** @brief UART FIFO debug register
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*
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* Bit | Name | Description
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* ------ | ------ | ----------------------------------------
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* 7-0 | data | Holding register or FIFO
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*/
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uint32_t debug; /* 0x0010 */
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};
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/* APBUART register bits. */
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/* Control register */
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#define APBUART_CTRL_FA (1 << 31)
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#define APBUART_CTRL_DB (1 << 11)
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#define APBUART_CTRL_RF (1 << 10)
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#define APBUART_CTRL_TF (1 << 9)
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#define APBUART_CTRL_LB (1 << 7)
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#define APBUART_CTRL_FL (1 << 6)
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#define APBUART_CTRL_PE (1 << 5)
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#define APBUART_CTRL_PS (1 << 4)
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#define APBUART_CTRL_TI (1 << 3)
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#define APBUART_CTRL_RI (1 << 2)
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#define APBUART_CTRL_TE (1 << 1)
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#define APBUART_CTRL_RE (1 << 0)
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/* Status register */
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#define APBUART_STATUS_RF (1 << 10)
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#define APBUART_STATUS_TF (1 << 9)
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#define APBUART_STATUS_RH (1 << 8)
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#define APBUART_STATUS_TH (1 << 7)
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#define APBUART_STATUS_FE (1 << 6)
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#define APBUART_STATUS_PE (1 << 5)
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#define APBUART_STATUS_OV (1 << 4)
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#define APBUART_STATUS_BR (1 << 3)
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#define APBUART_STATUS_TE (1 << 2)
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#define APBUART_STATUS_TS (1 << 1)
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#define APBUART_STATUS_DR (1 << 0)
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/* For APBUART implemented without FIFO */
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#define APBUART_STATUS_HOLD_REGISTER_EMPTY (1 << 2)
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struct apbuart_dev_cfg {
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struct apbuart_regs *regs;
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int interrupt;
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};
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struct apbuart_dev_data {
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int usefifo;
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};
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#define DEV_CFG(dev) \
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((const struct apbuart_dev_cfg *const)(dev)->config)
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#define DEV_DATA(dev) \
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((struct apbuart_dev_data *const)(dev)->data)
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/*
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* This routine waits for the TX holding register or TX FIFO to be ready and
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* then it writes a character to the data register.
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*/
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static void apbuart_poll_out(const struct device *dev, unsigned char x)
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{
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volatile struct apbuart_regs *regs = (void *) DEV_CFG(dev)->regs;
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if (DEV_DATA(dev)->usefifo) {
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/* Transmitter FIFO full flag is available. */
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while (regs->status & APBUART_STATUS_TF) {
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;
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}
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} else {
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/*
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* Transmitter "hold register empty" AKA "FIFO empty" flag is
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* available.
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*/
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while (!(regs->status & APBUART_STATUS_HOLD_REGISTER_EMPTY)) {
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;
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}
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}
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regs->data = x & 0xff;
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}
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static int apbuart_poll_in(const struct device *dev, unsigned char *c)
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{
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volatile struct apbuart_regs *regs = (void *) DEV_CFG(dev)->regs;
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if ((regs->status & APBUART_STATUS_DR) == 0) {
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return -1;
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}
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*c = regs->data & 0xff;
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return 0;
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}
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static int apbuart_err_check(const struct device *dev)
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{
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volatile struct apbuart_regs *regs = (void *) DEV_CFG(dev)->regs;
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const uint32_t status = regs->status;
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int err = 0;
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if (status & APBUART_STATUS_FE) {
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err |= UART_ERROR_FRAMING;
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}
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if (status & APBUART_STATUS_PE) {
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err |= UART_ERROR_PARITY;
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}
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if (status & APBUART_STATUS_OV) {
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err |= UART_ERROR_OVERRUN;
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}
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if (status & APBUART_STATUS_BR) {
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err |= UART_BREAK;
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}
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return err;
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}
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static int get_baud(volatile struct apbuart_regs *const regs)
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{
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unsigned int core_clk_hz;
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unsigned int scaler;
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scaler = regs->scaler;
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core_clk_hz = sys_clock_hw_cycles_per_sec();
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/* Calculate baud rate from generator "scaler" number */
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return core_clk_hz / ((scaler + 1) * 8);
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}
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static void set_baud(volatile struct apbuart_regs *const regs, uint32_t baud)
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{
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unsigned int core_clk_hz;
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unsigned int scaler;
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if (baud == 0) {
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return;
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}
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core_clk_hz = sys_clock_hw_cycles_per_sec();
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/* Calculate Baud rate generator "scaler" number */
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scaler = (((core_clk_hz * 10) / (baud * 8)) - 5) / 10;
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/* Set new baud rate by setting scaler */
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regs->scaler = scaler;
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}
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static int apbuart_configure(const struct device *dev,
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const struct uart_config *cfg)
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{
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volatile struct apbuart_regs *regs = (void *) DEV_CFG(dev)->regs;
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uint32_t ctrl = 0;
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uint32_t newctrl = 0;
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switch (cfg->parity) {
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case UART_CFG_PARITY_NONE:
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break;
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case UART_CFG_PARITY_EVEN:
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newctrl |= APBUART_CTRL_PE;
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break;
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case UART_CFG_PARITY_ODD:
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newctrl |= APBUART_CTRL_PE | APBUART_CTRL_PS;
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break;
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default:
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return -ENOTSUP;
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}
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if (cfg->stop_bits != UART_CFG_STOP_BITS_1) {
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return -ENOTSUP;
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}
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if (cfg->data_bits != UART_CFG_DATA_BITS_8) {
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return -ENOTSUP;
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}
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switch (cfg->flow_ctrl) {
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case UART_CFG_FLOW_CTRL_NONE:
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break;
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case UART_CFG_FLOW_CTRL_RTS_CTS:
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newctrl |= APBUART_CTRL_FL;
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break;
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default:
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return -ENOTSUP;
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}
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set_baud(regs, cfg->baudrate);
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ctrl = regs->ctrl;
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ctrl &= ~(APBUART_CTRL_PE | APBUART_CTRL_PS | APBUART_CTRL_FL);
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regs->ctrl = ctrl | newctrl;
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return 0;
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}
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static int apbuart_config_get(const struct device *dev, struct uart_config *cfg)
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{
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volatile struct apbuart_regs *regs = (void *) DEV_CFG(dev)->regs;
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const uint32_t ctrl = regs->ctrl;
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cfg->parity = UART_CFG_PARITY_NONE;
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if (ctrl & APBUART_CTRL_PE) {
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if (ctrl & APBUART_CTRL_PS) {
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cfg->parity = UART_CFG_PARITY_ODD;
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} else {
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cfg->parity = UART_CFG_PARITY_EVEN;
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}
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}
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cfg->flow_ctrl = UART_CFG_FLOW_CTRL_NONE;
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if (ctrl & APBUART_CTRL_FL) {
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cfg->flow_ctrl = UART_CFG_FLOW_CTRL_RTS_CTS;
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}
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cfg->baudrate = get_baud(regs);
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cfg->data_bits = UART_CFG_DATA_BITS_8;
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cfg->stop_bits = UART_CFG_STOP_BITS_1;
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return 0;
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}
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static int apbuart_init(const struct device *dev)
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{
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volatile struct apbuart_regs *regs = (void *) DEV_CFG(dev)->regs;
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const uint32_t APBUART_DEBUG_MASK = APBUART_CTRL_DB | APBUART_CTRL_FL;
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uint32_t dm;
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uint32_t ctrl;
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ctrl = regs->ctrl;
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DEV_DATA(dev)->usefifo = !!(ctrl & APBUART_CTRL_FA);
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/* NOTE: CTRL_FL has reset value 0. CTRL_DB has no reset value. */
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dm = ctrl & APBUART_DEBUG_MASK;
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if (dm == APBUART_DEBUG_MASK) {
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/* Debug mode enabled so assume APBUART already initialized. */
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;
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} else {
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regs->ctrl = APBUART_CTRL_TE | APBUART_CTRL_RE;
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}
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regs->status = 0;
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return 0;
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}
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/* Driver API defined in uart.h */
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static const struct uart_driver_api apbuart_driver_api = {
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.poll_in = apbuart_poll_in,
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.poll_out = apbuart_poll_out,
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.err_check = apbuart_err_check,
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.configure = apbuart_configure,
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.config_get = apbuart_config_get,
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};
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#define APBUART_INIT(index) \
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static const struct apbuart_dev_cfg apbuart##index##_config = { \
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.regs = (struct apbuart_regs *) \
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DT_INST_REG_ADDR(index), \
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.interrupt = DT_INST_IRQN(index), \
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}; \
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\
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static struct apbuart_dev_data apbuart##index##_data = { \
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.usefifo = 0, \
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}; \
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\
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DEVICE_AND_API_INIT(uart_apbuart_##index, \
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DT_INST_LABEL(index), \
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&apbuart_init, \
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&apbuart##index##_data, \
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&apbuart##index##_config, \
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PRE_KERNEL_1, \
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CONFIG_KERNEL_INIT_PRIORITY_DEVICE, \
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&apbuart_driver_api);
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DT_INST_FOREACH_STATUS_OKAY(APBUART_INIT)
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