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  • 2020-06-01
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serial_lpuart.c

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  • Forked from Reform / reform-boundary-uboot
    29231 commits behind the upstream repository.
    serial_lpuart.c 2.26 KiB
    /*
     * Copyright 2013 Freescale Semiconductor, Inc.
     *
     * SPDX-License-Identifier:	GPL-2.0+
     */
    
    #include <common.h>
    #include <watchdog.h>
    #include <asm/io.h>
    #include <serial.h>
    #include <linux/compiler.h>
    #include <asm/arch/imx-regs.h>
    #include <asm/arch/clock.h>
    
    #define US1_TDRE        (1 << 7)
    #define US1_RDRF        (1 << 5)
    #define UC2_TE          (1 << 3)
    #define UC2_RE          (1 << 2)
    
    DECLARE_GLOBAL_DATA_PTR;
    
    struct lpuart_fsl *base = (struct lpuart_fsl *)LPUART_BASE;
    
    static void lpuart_serial_setbrg(void)
    {
    	u32 clk = mxc_get_clock(MXC_UART_CLK);
    	u16 sbr;
    
    	if (!gd->baudrate)
    		gd->baudrate = CONFIG_BAUDRATE;
    
    	sbr = (u16)(clk / (16 * gd->baudrate));
    	/* place adjustment later - n/32 BRFA */
    
    	__raw_writeb(sbr >> 8, &base->ubdh);
    	__raw_writeb(sbr & 0xff, &base->ubdl);
    }
    
    static int lpuart_serial_getc(void)
    {
    	u8 status;
    
    	while (!(__raw_readb(&base->us1) & US1_RDRF))
    		WATCHDOG_RESET();
    
    	status = __raw_readb(&base->us1);
    	status |= US1_RDRF;
    	__raw_writeb(status, &base->us1);
    
    	return __raw_readb(&base->ud);
    }
    
    static void lpuart_serial_putc(const char c)
    {
    	if (c == '\n')
    		serial_putc('\r');
    
    	while (!(__raw_readb(&base->us1) & US1_TDRE))
    		WATCHDOG_RESET();
    
    	__raw_writeb(c, &base->ud);
    }
    
    /*
     * Test whether a character is in the RX buffer
     */
    static int lpuart_serial_tstc(void)
    {
    	if (__raw_readb(&base->urcfifo) == 0)
    		return 0;
    
    	return 1;
    }
    
    /*
     * Initialise the serial port with the given baudrate. The settings
     * are always 8 data bits, no parity, 1 stop bit, no start bits.
     */
    static int lpuart_serial_init(void)
    {
    	u8 ctrl;
    
    	ctrl = __raw_readb(&base->uc2);
    	ctrl &= ~UC2_RE;
    	ctrl &= ~UC2_TE;
    	__raw_writeb(ctrl, &base->uc2);
    
    	__raw_writeb(0, &base->umodem);
    	__raw_writeb(0, &base->uc1);
    
    	/* provide data bits, parity, stop bit, etc */
    
    	serial_setbrg();
    
    	__raw_writeb(UC2_RE | UC2_TE, &base->uc2);
    
    	return 0;
    }
    
    static struct serial_device lpuart_serial_drv = {
    	.name = "lpuart_serial",
    	.start = lpuart_serial_init,
    	.stop = NULL,
    	.setbrg = lpuart_serial_setbrg,
    	.putc = lpuart_serial_putc,
    	.puts = default_serial_puts,
    	.getc = lpuart_serial_getc,
    	.tstc = lpuart_serial_tstc,
    };
    
    void lpuart_serial_initialize(void)
    {
    	serial_register(&lpuart_serial_drv);
    }
    
    __weak struct serial_device *default_serial_console(void)
    {
    	return &lpuart_serial_drv;
    }