path: root/drivers/serial/bfin_sport_uart.c

/*
 * Blackfin On-Chip Sport Emulated UART Driver
 *
 * Copyright 2006-2009 Analog Devices Inc.
 *
 * Enter bugs at http://blackfin.uclinux.org/
 *
 * Licensed under the GPL-2 or later.
 */

/*
 * This driver and the hardware supported are in term of EE-191 of ADI.
 * http://www.analog.com/static/imported-files/application_notes/EE191.pdf 
 * This application note describe how to implement a UART on a Sharc DSP,
 * but this driver is implemented on Blackfin Processor.
 * Transmit Frame Sync is not used by this driver to transfer data out.
 */

/* #define DEBUG */

#define DRV_NAME "bfin-sport-uart"
#define DEVICE_NAME	"ttySS"
#define pr_fmt(fmt) DRV_NAME ": " fmt

#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>

#include <asm/bfin_sport.h>
#include <asm/delay.h>
#include <asm/portmux.h>

#include "bfin_sport_uart.h"

struct sport_uart_port {
	struct uart_port	port;
	int			err_irq;
	unsigned short		csize;
	unsigned short		rxmask;
	unsigned short		txmask1;
	unsigned short		txmask2;
	unsigned char		stopb;
/*	unsigned char		parib; */
#ifdef CONFIG_SERIAL_BFIN_SPORT_CTSRTS
	int cts_pin;
	int rts_pin;
#endif
};

static int sport_uart_tx_chars(struct sport_uart_port *up);
static void sport_stop_tx(struct uart_port *port);

static inline void tx_one_byte(struct sport_uart_port *up, unsigned int value)
{
	pr_debug("%s value:%x, mask1=0x%x, mask2=0x%x\n", __func__, value,
		up->txmask1, up->txmask2);

	/* Place Start and Stop bits */
	__asm__ __volatile__ (
		"%[val] <<= 1;"
		"%[val] = %[val] & %[mask1];"
		"%[val] = %[val] | %[mask2];"
		: [val]"+d"(value)
		: [mask1]"d"(up->txmask1), [mask2]"d"(up->txmask2)
		: "ASTAT"
	);
	pr_debug("%s value:%x\n", __func__, value);

	SPORT_PUT_TX(up, value);
}

static inline unsigned char rx_one_byte(struct sport_uart_port *up)
{
	unsigned int value;
	unsigned char extract;
	u32 tmp_mask1, tmp_mask2, tmp_shift, tmp;

	if ((up->csize + up->stopb) > 7)
		value = SPORT_GET_RX32(up);
	else
		value = SPORT_GET_RX(up);

	pr_debug("%s value:%x, cs=%d, mask=0x%x\n", __func__, value,
		up->csize, up->rxmask);

	/* Extract data */
	__asm__ __volatile__ (
		"%[extr] = 0;"
		"%[mask1] = %[rxmask];"
		"%[mask2] = 0x0200(Z);"
		"%[shift] = 0;"
		"LSETUP(.Lloop_s, .Lloop_e) LC0 = %[lc];"
		".Lloop_s:"
		"%[tmp] = extract(%[val], %[mask1].L)(Z);"
		"%[tmp] <<= %[shift];"
		"%[extr] = %[extr] | %[tmp];"
		"%[mask1] = %[mask1] - %[mask2];"
		".Lloop_e:"
		"%[shift] += 1;"
		: [extr]"=&d"(extract), [shift]"=&d"(tmp_shift), [tmp]"=&d"(tmp),
		  [mask1]"=&d"(tmp_mask1), [mask2]"=&d"(tmp_mask2)
		: [val]"d"(value), [rxmask]"d"(up->rxmask), [lc]"a"(up->csize)
		: "ASTAT", "LB0", "LC0", "LT0"
	);

	pr_debug("	extract:%x\n", extract);
	return extract;
}

static int sport_uart_setup(struct sport_uart_port *up, int size, int baud_rate)
{
	int tclkdiv, rclkdiv;
	unsigned int sclk = get_sclk();

	/* Set TCR1 and TCR2, TFSR is not enabled for uart */
	SPORT_PUT_TCR1(up, (LATFS | ITFS | TFSR | TLSBIT | ITCLK));
	SPORT_PUT_TCR2(up, size + 1);
	pr_debug("%s TCR1:%x, TCR2:%x\n", __func__, SPORT_GET_TCR1(up), SPORT_GET_TCR2(up));

	/* Set RCR1 and RCR2 */
	SPORT_PUT_RCR1(up, (RCKFE | LARFS | LRFS | RFSR | IRCLK));
	SPORT_PUT_RCR2(up, (size + 1) * 2 - 1);
	pr_debug("%s RCR1:%x, RCR2:%x\n", __func__, SPORT_GET_RCR1(up), SPORT_GET_RCR2(up));

	tclkdiv = sclk / (2 * baud_rate) - 1;
	/* The actual uart baud rate of devices vary between +/-2%. The sport
	 * RX sample rate should be faster than the double of the worst case,
	 * otherwise, wrong data are received. So, set sport RX clock to be
	 * 3% faster.
	 */
	rclkdiv = sclk / (2 * baud_rate * 2 * 97 / 100) - 1;
	SPORT_PUT_TCLKDIV(up, tclkdiv);
	SPORT_PUT_RCLKDIV(up, rclkdiv);
	SSYNC();
	pr_debug("%s sclk:%d, baud_rate:%d, tclkdiv:%d, rclkdiv:%d\n",
			__func__, sclk, baud_rate, tclkdiv, rclkdiv);

	return 0;
}

static irqreturn_t sport_uart_rx_irq(int irq, void *dev_id)
{
	struct sport_uart_port *up = dev_id;
	struct tty_struct *tty = up->port.state->port.tty;
	unsigned int ch;

	spin_lock(&up->port.lock);

	while (SPORT_GET_STAT(up) & RXNE) {
		ch