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drivers/uart/pl011.c Perform basic UART init

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Configure UART baud rate, Line Control register as 8n1 with FIFO
enable and enable UART TX and RX.

Change-Id: I090344a20430dc370a0b93ff7fbbae54111fae24
Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79406
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
This commit is contained in:
Naresh Solanki
2023-08-10 13:21:44 +02:00
committed by Lean Sheng Tan
parent 3e25f85d68
commit 5466261019
1 changed files with 32 additions and 0 deletions
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32
src/drivers/uart/pl011.c
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@@ -7,6 +7,38 @@
void uart_init(unsigned int idx) void uart_init(unsigned int idx)
{ {
struct pl011_uart *regs = uart_platform_baseptr(idx);
uint32_t tmp;
if (!regs)
return;
/* Disable UART */
tmp = read32(&regs->cr);
tmp &= ~PL011_UARTCR_UARTEN;
write32(&regs->cr, tmp);
/*
* Program Divisor
* As per: PL011 Technical reference manual:
* BAUDDIV = (Fuartclk / (16 * baud_rate))
* Considering 6 bits(64) for UARTFBRD
* BAUDDIV = (Fuartclk * 4 / baud_rate)
*/
tmp = uart_platform_refclk() * 4 / get_uart_baudrate();
write32(&regs->ibrd, tmp >> 6);
write32(&regs->fbrd, tmp & 0x3f);
/* Program LINE Control 8n1, FIFO enable */
tmp = read32(&regs->lcr_h);
tmp |= PL011_LINE_CONTROL;
write32(&regs->lcr_h, tmp);
/* Enable UART */
tmp = read32(&regs->cr);
tmp |= PL011_UARTCR_UARTEN | PL011_UARTCR_RXE | PL011_UARTCR_TXE;
write32(&regs->cr, tmp);
} }
void uart_tx_byte(unsigned int idx, unsigned char data) void uart_tx_byte(unsigned int idx, unsigned char data)