serial_scc.c

嵌入式ARM的一些源代码

/*
 * (C) Copyright 2000
 * Wolfgang Denk, DENX Software Engineering, [e-mail].
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 *
 * Hacked for MPC8260 by [e-mail], 19-Oct-00.
 */

/*
 * Minimal serial functions needed to use one of the SCC ports
 * as serial console interface.
 */

#include <ppcboot.h>
#include <mpc8260.h>
#include <asm/cpm_8260.h>

#if defined(CONFIG_CONS_ON_SCC)

#if CONFIG_CONS_INDEX == 1	/* Console on SCC1 */

#define SCC_INDEX		0
#define PROFF_SCC		PROFF_SCC1
#define CMXSCR_MASK		(CMXSCR_GR1|CMXSCR_SC1|\
					CMXSCR_RS1CS_MSK|CMXSCR_TS1CS_MSK)
#define CMXSCR_VALUE		(CMXSCR_RS1CS_BRG1|CMXSCR_TS1CS_BRG1)
#define CPM_CR_SCC_PAGE		CPM_CR_SCC1_PAGE
#define CPM_CR_SCC_SBLOCK	CPM_CR_SCC1_SBLOCK

#elif CONFIG_CONS_INDEX == 2	/* Console on SCC2 */

#define SCC_INDEX		1
#define PROFF_SCC		PROFF_SCC2
#define CMXSCR_MASK		(CMXSCR_GR2|CMXSCR_SC2|\
					CMXSCR_RS2CS_MSK|CMXSCR_TS2CS_MSK)
#define CMXSCR_VALUE		(CMXSCR_RS2CS_BRG1|CMXSCR_TS2CS_BRG1)
#define CPM_CR_SCC_PAGE		CPM_CR_SCC2_PAGE
#define CPM_CR_SCC_SBLOCK	CPM_CR_SCC2_SBLOCK

#elif CONFIG_CONS_INDEX == 3	/* Console on SCC3 */

#define SCC_INDEX		2
#define PROFF_SCC		PROFF_SCC3
#define CMXSCR_MASK		(CMXSCR_GR3|CMXSCR_SC3|\
					CMXSCR_RS3CS_MSK|CMXSCR_TS3CS_MSK)
#define CMXSCR_VALUE		(CMXSCR_RS3CS_BRG1|CMXSCR_TS3CS_BRG1)
#define CPM_CR_SCC_PAGE		CPM_CR_SCC3_PAGE
#define CPM_CR_SCC_SBLOCK	CPM_CR_SCC3_SBLOCK

#elif CONFIG_CONS_INDEX == 4	/* Console on SCC4 */

#define SCC_INDEX		3
#define PROFF_SCC		PROFF_SCC4
#define CMXSCR_MASK		(CMXSCR_GR4|CMXSCR_SC4|\
					CMXSCR_RS4CS_MSK|CMXSCR_TS4CS_MSK)
#define CMXSCR_VALUE		(CMXSCR_RS4CS_BRG1|CMXSCR_TS4CS_BRG1)
#define CPM_CR_SCC_PAGE		CPM_CR_SCC4_PAGE
#define CPM_CR_SCC_SBLOCK	CPM_CR_SCC4_SBLOCK

#else

#error "console not correctly defined"

#endif

void
serial_init (ulong cpu_clock, int baudrate)
{
        volatile immap_t *im = (immap_t *)CFG_IMMR;
	volatile scc_t *sp;
	volatile scc_uart_t *up;
	volatile cbd_t *tbdf, *rbdf;
	volatile cpm8260_t *cp = &(im->im_cpm);
	uint	dpaddr;

	/* initialize pointers to SCC */

	sp = (scc_t *) &(im->im_scc[SCC_INDEX]);
	up = (scc_uart_t *)&im->im_dprambase[PROFF_SCC];

	/* Disable transmitter/receiver.
	*/
	sp->scc_gsmrl &= ~(SCC_GSMRL_ENR | SCC_GSMRL_ENT);

	/* Set up the baud rate generator.
	*/
	serial_setbrg (cpu_clock, baudrate);

	/* Allocate space for two buffer descriptors in the DP ram.
	 * For now, this address seems OK, but it may have to
	 * change with newer versions of the firmware.
	 * damm: allocating space after the two buffers for rx/tx data
	 */

	dpaddr = 0x800;

	/* Set the physical address of the host memory buffers in
	 * the buffer descriptors.
	 */
	rbdf = (cbd_t *)&im->im_dprambase[dpaddr];
	rbdf->cbd_bufaddr = (uint) (rbdf+2);
	rbdf->cbd_sc = BD_SC_EMPTY | BD_SC_WRAP;
	tbdf = rbdf + 1;
	tbdf->cbd_bufaddr = ((uint) (rbdf+2)) + 1;
	tbdf->cbd_sc = BD_SC_WRAP;

	/* Set up the uart parameters in the parameter ram.
	*/
	up->scc_genscc.scc_rbase = dpaddr;
	up->scc_genscc.scc_tbase = dpaddr+sizeof(cbd_t);
	up->scc_genscc.scc_rfcr = CPMFCR_EB;
	up->scc_genscc.scc_tfcr = CPMFCR_EB;
	up->scc_genscc.scc_mrblr = 1;
	up->scc_maxidl = 0;
	up->scc_brkcr = 1;
	up->scc_parec = 0;
	up->scc_frmec = 0;
	up->scc_nosec = 0;
	up->scc_brkec = 0;
	up->scc_uaddr1 = 0;
	up->scc_uaddr2 = 0;
	up->scc_toseq = 0;
	up->scc_char1 = up->scc_char2 = up->scc_char3 = up->scc_char4 = 0x8000;
	up->scc_char5 = up->scc_char6 = up->scc_char7 = up->scc_char8 = 0x8000;
	up->scc_rccm = 0xc0ff;

	/* Mask all interrupts and remove anything pending.
	*/
	sp->scc_sccm = 0;
	sp->scc_scce = 0xffff;

	/* Set 8 bit FIFO, 16 bit oversampling and UART mode.
	*/
	sp->scc_gsmrh = SCC_GSMRH_RFW;	/* 8 bit FIFO */
	sp->scc_gsmrl = \
		SCC_GSMRL_TDCR_16 | SCC_GSMRL_RDCR_16 | SCC_GSMRL_MODE_UART;

	/* Set CTS flow control, 1 stop bit, 8 bit character length,
	 * normal async UART mode, no parity
	 */
	sp->scc_psmr = SCU_PSMR_FLC | SCU_PSMR_CL;

	/* execute the "Init Rx and Tx params" CP command.
	*/

	while (cp->cp_cpcr & CPM_CR_FLG)  /* wait if cp is busy */
	  ;

	cp->cp_cpcr = mk_cr_cmd(CPM_CR_SCC_PAGE, CPM_CR_SCC_SBLOCK,
					0, CPM_CR_INIT_TRX) | CPM_CR_FLG;

	while (cp->cp_cpcr & CPM_CR_FLG)  /* wait if cp is busy */
	  ;

	/* Enable transmitter/receiver.
	*/
	sp->scc_gsmrl |= SCC_GSMRL_ENR | SCC_GSMRL_ENT;
}

void
serial_setbrg (ulong cpu_clock, int baudrate)
{
        volatile immap_t *im = (immap_t *)CFG_IMMR;
	init_data_t *idata =
		(init_data_t *)(CFG_INIT_RAM_ADDR+CFG_INIT_DATA_OFFSET);
	ulong i;

	/* put the SCC channel into NMSI (non multiplexd serial interface)
	 * mode and wire the selected SCC Tx and Rx clocks to BRG1 (15-15).
	 */
	im->im_cpmux.cmx_scr = (im->im_cpmux.cmx_scr&~CMXSCR_MASK)|CMXSCR_VALUE;

	/* configure baud rate generator 1 (16-2).
	 * the uart must be configured for 16x oversampling (hence the
	 * divide by 16 below). I also round all divisions, rather than
	 * truncate - hopefully that will provide a slightly more accurate
	 * clock divider.
	 */
#if defined(CFG_CLKS_IN_HZ)
	i = (idata->brg_clk + 15) / 16;
#else
	i = ((idata->brg_clk * 1000000) + 15) / 16;
#endif

	i = (i + baudrate - 1) / baudrate;

	im->im_brgc1 = (((i - 1) & 0xfff) << 1) | CPM_BRG_EN;
}

void
serial_putc(const char c)
{
	volatile scc_uart_t	*up;
	volatile cbd_t		*tbdf;
        volatile immap_t	*im;

	if (c == '\n')
		serial_putc ('\r');

        im = (immap_t *)CFG_IMMR;
	up = (scc_uart_t *)&im->im_dprambase[PROFF_SCC];
	tbdf = (cbd_t *)&im->im_dprambase[up->scc_genscc.scc_tbase];

	/* Wait for last character to go.
	 */
	while (tbdf->cbd_sc & BD_SC_READY)
		;

	/* Load the character into the transmit buffer.
	 */
	*(volatile char *)tbdf->cbd_bufaddr = c;
	tbdf->cbd_datlen = 1;
	tbdf->cbd_sc |= BD_SC_READY;
}

void
serial_puts (const char *s)
{
	while (*s) {
		serial_putc (*s++);
	}
}

int
serial_getc(void)
{
	volatile cbd_t		*rbdf;
	volatile scc_uart_t	*up;
        volatile immap_t	*im;
	unsigned char		c;

        im = (immap_t *)CFG_IMMR;
	up = (scc_uart_t *)&im->im_dprambase[PROFF_SCC];
	rbdf = (cbd_t *)&im->im_dprambase[up->scc_genscc.scc_rbase];

	/* Wait for character to show up.
	 */
	while (rbdf->cbd_sc & BD_SC_EMPTY)
		;

	/* Grab the char and clear the buffer again.
	 */
	c = *(volatile unsigned char *)rbdf->cbd_bufaddr;
	rbdf->cbd_sc |= BD_SC_EMPTY;

	return (c);
}

int
serial_tstc()
{
	volatile cbd_t		*rbdf;
	volatile scc_uart_t	*up;
        volatile immap_t	*im;

        im = (immap_t *)CFG_IMMR;
	up = (scc_uart_t *)&im->im_dprambase[PROFF_SCC];
	rbdf = (cbd_t *)&im->im_dprambase[up->scc_genscc.scc_rbase];

	return ((rbdf->cbd_sc & BD_SC_EMPTY) == 0);
}

#endif	/* CONFIG_CONS_ON_SCC */