Merge branch 'renesas/drivers-sci2' into next/drivers

* renesas/drivers-sci2:
  serial: sh-sci: Rework baud rate calculation
  serial: sh-sci: Compute overrun_bit without using baud rate algo
  serial: sh-sci: Remove unused GPIO request code
  serial: sh-sci: Move overrun_bit and error_mask fields out of pdata
  serial: sh-sci: Support resources passed through platform resources
  serial: sh-sci: Don't check IRQ in verify port operation
  serial: sh-sci: Set the UPF_FIXED_PORT flag
  serial: sh-sci: Remove duplicate interrupt check in verify port op
  serial: sh-sci: Simplify baud rate calculation algorithms
  serial: sh-sci: Remove baud rate calculation algorithm 5
  serial: sh-sci: Sort headers alphabetically
  serial: sh-sci: Convert to clk_prepare/unprepare
  serial: sh-sci: Don't enable/disable port from within break timer
  serial: sh-sci: Fix warnings due to improper casts and printk formats
This commit is contained in:
Olof Johansson 2014-01-02 10:54:20 -08:00
commit 6878e0c0a5
3 changed files with 178 additions and 206 deletions

View File

@ -23,35 +23,34 @@
#undef DEBUG
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/sh_dma.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/sysrq.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/console.h>
#include <linux/platform_device.h>
#include <linux/serial_sci.h>
#include <linux/notifier.h>
#include <linux/pm_runtime.h>
#include <linux/cpufreq.h>
#include <linux/clk.h>
#include <linux/console.h>
#include <linux/ctype.h>
#include <linux/err.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/major.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/notifier.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/scatterlist.h>
#include <linux/serial.h>
#include <linux/serial_sci.h>
#include <linux/sh_dma.h>
#include <linux/slab.h>
#include <linux/gpio.h>
#include <linux/string.h>
#include <linux/sysrq.h>
#include <linux/timer.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#ifdef CONFIG_SUPERH
#include <asm/sh_bios.h>
@ -64,6 +63,10 @@ struct sci_port {
/* Platform configuration */
struct plat_sci_port *cfg;
int overrun_bit;
unsigned int error_mask;
unsigned int sampling_rate;
/* Break timer */
struct timer_list break_timer;
@ -74,8 +77,8 @@ struct sci_port {
/* Function clock */
struct clk *fclk;
int irqs[SCIx_NR_IRQS];
char *irqstr[SCIx_NR_IRQS];
char *gpiostr[SCIx_NR_FNS];
struct dma_chan *chan_tx;
struct dma_chan *chan_rx;
@ -421,9 +424,9 @@ static void sci_port_enable(struct sci_port *sci_port)
pm_runtime_get_sync(sci_port->port.dev);
clk_enable(sci_port->iclk);
clk_prepare_enable(sci_port->iclk);
sci_port->port.uartclk = clk_get_rate(sci_port->iclk);
clk_enable(sci_port->fclk);
clk_prepare_enable(sci_port->fclk);
}
static void sci_port_disable(struct sci_port *sci_port)
@ -431,8 +434,16 @@ static void sci_port_disable(struct sci_port *sci_port)
if (!sci_port->port.dev)
return;
clk_disable(sci_port->fclk);
clk_disable(sci_port->iclk);
/* Cancel the break timer to ensure that the timer handler will not try
* to access the hardware with clocks and power disabled. Reset the
* break flag to make the break debouncing state machine ready for the
* next break.
*/
del_timer_sync(&sci_port->break_timer);
sci_port->break_flag = 0;
clk_disable_unprepare(sci_port->fclk);
clk_disable_unprepare(sci_port->iclk);
pm_runtime_put_sync(sci_port->port.dev);
}
@ -557,7 +568,7 @@ static inline int sci_rxd_in(struct uart_port *port)
return 1;
/* Cast for ARM damage */
return !!__raw_readb((void __iomem *)s->cfg->port_reg);
return !!__raw_readb((void __iomem *)(uintptr_t)s->cfg->port_reg);
}
/* ********************************************************************** *
@ -733,8 +744,6 @@ static void sci_break_timer(unsigned long data)
{
struct sci_port *port = (struct sci_port *)data;
sci_port_enable(port);
if (sci_rxd_in(&port->port) == 0) {
port->break_flag = 1;
sci_schedule_break_timer(port);
@ -744,8 +753,6 @@ static void sci_break_timer(unsigned long data)
sci_schedule_break_timer(port);
} else
port->break_flag = 0;
sci_port_disable(port);
}
static int sci_handle_errors(struct uart_port *port)
@ -755,19 +762,15 @@ static int sci_handle_errors(struct uart_port *port)
struct tty_port *tport = &port->state->port;
struct sci_port *s = to_sci_port(port);
/*
* Handle overruns, if supported.
*/
if (s->cfg->overrun_bit != SCIx_NOT_SUPPORTED) {
if (status & (1 << s->cfg->overrun_bit)) {
port->icount.overrun++;
/* Handle overruns */
if (status & (1 << s->overrun_bit)) {
port->icount.overrun++;
/* overrun error */
if (tty_insert_flip_char(tport, 0, TTY_OVERRUN))
copied++;
/* overrun error */
if (tty_insert_flip_char(tport, 0, TTY_OVERRUN))
copied++;
dev_notice(port->dev, "overrun error");
}
dev_notice(port->dev, "overrun error");
}
if (status & SCxSR_FER(port)) {
@ -829,7 +832,7 @@ static int sci_handle_fifo_overrun(struct uart_port *port)
if (!reg->size)
return 0;
if ((serial_port_in(port, SCLSR) & (1 << s->cfg->overrun_bit))) {
if ((serial_port_in(port, SCLSR) & (1 << s->overrun_bit))) {
serial_port_out(port, SCLSR, 0);
port->icount.overrun++;
@ -1075,19 +1078,19 @@ static int sci_request_irq(struct sci_port *port)
for (i = j = 0; i < SCIx_NR_IRQS; i++, j++) {
struct sci_irq_desc *desc;
unsigned int irq;
int irq;
if (SCIx_IRQ_IS_MUXED(port)) {
i = SCIx_MUX_IRQ;
irq = up->irq;
} else {
irq = port->cfg->irqs[i];
irq = port->irqs[i];
/*
* Certain port types won't support all of the
* available interrupt sources.
*/
if (unlikely(!irq))
if (unlikely(irq < 0))
continue;
}
@ -1112,7 +1115,7 @@ static int sci_request_irq(struct sci_port *port)
out_noirq:
while (--i >= 0)
free_irq(port->cfg->irqs[i], port);
free_irq(port->irqs[i], port);
out_nomem:
while (--j >= 0)
@ -1130,16 +1133,16 @@ static void sci_free_irq(struct sci_port *port)
* IRQ first.
*/
for (i = 0; i < SCIx_NR_IRQS; i++) {
unsigned int irq = port->cfg->irqs[i];
int irq = port->irqs[i];
/*
* Certain port types won't support all of the available
* interrupt sources.
*/
if (unlikely(!irq))
if (unlikely(irq < 0))
continue;
free_irq(port->cfg->irqs[i], port);
free_irq(port->irqs[i], port);
kfree(port->irqstr[i]);
if (SCIx_IRQ_IS_MUXED(port)) {
@ -1149,67 +1152,6 @@ static void sci_free_irq(struct sci_port *port)
}
}
static const char *sci_gpio_names[SCIx_NR_FNS] = {
"sck", "rxd", "txd", "cts", "rts",
};
static const char *sci_gpio_str(unsigned int index)
{
return sci_gpio_names[index];
}
static void sci_init_gpios(struct sci_port *port)
{
struct uart_port *up = &port->port;
int i;
if (!port->cfg)
return;
for (i = 0; i < SCIx_NR_FNS; i++) {
const char *desc;
int ret;
if (!port->cfg->gpios[i])
continue;
desc = sci_gpio_str(i);
port->gpiostr[i] = kasprintf(GFP_KERNEL, "%s:%s",
dev_name(up->dev), desc);
/*
* If we've failed the allocation, we can still continue
* on with a NULL string.
*/
if (!port->gpiostr[i])
dev_notice(up->dev, "%s string allocation failure\n",
desc);
ret = gpio_request(port->cfg->gpios[i], port->gpiostr[i]);
if (unlikely(ret != 0)) {
dev_notice(up->dev, "failed %s gpio request\n", desc);
/*
* If we can't get the GPIO for whatever reason,
* no point in keeping the verbose string around.
*/
kfree(port->gpiostr[i]);
}
}
}
static void sci_free_gpios(struct sci_port *port)
{
int i;
for (i = 0; i < SCIx_NR_FNS; i++)
if (port->cfg->gpios[i]) {
gpio_free(port->cfg->gpios[i]);
kfree(port->gpiostr[i]);
}
}
static unsigned int sci_tx_empty(struct uart_port *port)
{
unsigned short status = serial_port_in(port, SCxSR);
@ -1309,7 +1251,7 @@ static int sci_dma_rx_push(struct sci_port *s, size_t count)
}
if (room < count)
dev_warn(port->dev, "Rx overrun: dropping %u bytes\n",
dev_warn(port->dev, "Rx overrun: dropping %zu bytes\n",
count - room);
if (!room)
return room;
@ -1442,7 +1384,7 @@ static void work_fn_rx(struct work_struct *work)
int count;
chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
dev_dbg(port->dev, "Read %u bytes with cookie %d\n",
dev_dbg(port->dev, "Read %zu bytes with cookie %d\n",
sh_desc->partial, sh_desc->cookie);
spin_lock_irqsave(&port->lock, flags);
@ -1655,7 +1597,7 @@ static void rx_timer_fn(unsigned long arg)
if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {
scr &= ~0x4000;
enable_irq(s->cfg->irqs[1]);
enable_irq(s->irqs[SCIx_RXI_IRQ]);
}
serial_port_out(port, SCSCR, scr | SCSCR_RIE);
dev_dbg(port->dev, "DMA Rx timed out\n");
@ -1691,16 +1633,17 @@ static void sci_request_dma(struct uart_port *port)
s->chan_tx = chan;
sg_init_table(&s->sg_tx, 1);
/* UART circular tx buffer is an aligned page. */
BUG_ON((int)port->state->xmit.buf & ~PAGE_MASK);
BUG_ON((uintptr_t)port->state->xmit.buf & ~PAGE_MASK);
sg_set_page(&s->sg_tx, virt_to_page(port->state->xmit.buf),
UART_XMIT_SIZE, (int)port->state->xmit.buf & ~PAGE_MASK);
UART_XMIT_SIZE,
(uintptr_t)port->state->xmit.buf & ~PAGE_MASK);
nent = dma_map_sg(port->dev, &s->sg_tx, 1, DMA_TO_DEVICE);
if (!nent)
sci_tx_dma_release(s, false);
else
dev_dbg(port->dev, "%s: mapped %d@%p to %x\n", __func__,
sg_dma_len(&s->sg_tx),
port->state->xmit.buf, sg_dma_address(&s->sg_tx));
dev_dbg(port->dev, "%s: mapped %d@%p to %pad\n", __func__,
sg_dma_len(&s->sg_tx), port->state->xmit.buf,
&sg_dma_address(&s->sg_tx));
s->sg_len_tx = nent;
@ -1740,7 +1683,7 @@ static void sci_request_dma(struct uart_port *port)
sg_init_table(sg, 1);
sg_set_page(sg, virt_to_page(buf[i]), s->buf_len_rx,
(int)buf[i] & ~PAGE_MASK);
(uintptr_t)buf[i] & ~PAGE_MASK);
sg_dma_address(sg) = dma[i];
}
@ -1808,20 +1751,21 @@ static void sci_shutdown(struct uart_port *port)
sci_free_irq(s);
}
static unsigned int sci_scbrr_calc(unsigned int algo_id, unsigned int bps,
static unsigned int sci_scbrr_calc(struct sci_port *s, unsigned int bps,
unsigned long freq)
{
switch (algo_id) {
if (s->sampling_rate)
return DIV_ROUND_CLOSEST(freq, s->sampling_rate * bps) - 1;
switch (s->cfg->scbrr_algo_id) {
case SCBRR_ALGO_1:
return ((freq + 16 * bps) / (16 * bps) - 1);
return freq / (16 * bps);
case SCBRR_ALGO_2:
return ((freq + 16 * bps) / (32 * bps) - 1);
return DIV_ROUND_CLOSEST(freq, 32 * bps) - 1;
case SCBRR_ALGO_3:
return (((freq * 2) + 16 * bps) / (16 * bps) - 1);
return freq / (8 * bps);
case SCBRR_ALGO_4:
return (((freq * 2) + 16 * bps) / (32 * bps) - 1);
case SCBRR_ALGO_5:
return (((freq * 1000 / 32) / bps) - 1);
return DIV_ROUND_CLOSEST(freq, 16 * bps) - 1;
}
/* Warn, but use a safe default */
@ -1903,12 +1847,11 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
baud = uart_get_baud_rate(port, termios, old, 0, max_baud);
if (likely(baud && port->uartclk)) {
if (s->cfg->scbrr_algo_id == SCBRR_ALGO_6) {
if (s->cfg->type == PORT_HSCIF) {
sci_baud_calc_hscif(baud, port->uartclk, &t, &srr,
&cks);
} else {
t = sci_scbrr_calc(s->cfg->scbrr_algo_id, baud,
port->uartclk);
t = sci_scbrr_calc(s, baud, port->uartclk);
for (cks = 0; t >= 256 && cks <= 3; cks++)
t >>= 2;
}
@ -2115,10 +2058,6 @@ static void sci_config_port(struct uart_port *port, int flags)
static int sci_verify_port(struct uart_port *port, struct serial_struct *ser)
{
struct sci_port *s = to_sci_port(port);
if (ser->irq != s->cfg->irqs[SCIx_TXI_IRQ] || ser->irq > nr_irqs)
return -EINVAL;
if (ser->baud_base < 2400)
/* No paper tape reader for Mitch.. */
return -EINVAL;
@ -2151,11 +2090,13 @@ static struct uart_ops sci_uart_ops = {
};
static int sci_init_single(struct platform_device *dev,
struct sci_port *sci_port,
unsigned int index,
struct plat_sci_port *p)
struct sci_port *sci_port, unsigned int index,
struct plat_sci_port *p, bool early)
{
struct uart_port *port = &sci_port->port;
const struct resource *res;
unsigned int sampling_rate;
unsigned int i;
int ret;
sci_port->cfg = p;
@ -2164,22 +2105,36 @@ static int sci_init_single(struct platform_device *dev,
port->iotype = UPIO_MEM;
port->line = index;
switch (p->type) {
case PORT_SCIFB:
port->fifosize = 256;
break;
case PORT_HSCIF:
port->fifosize = 128;
break;
case PORT_SCIFA:
port->fifosize = 64;
break;
case PORT_SCIF:
port->fifosize = 16;
break;
default:
port->fifosize = 1;
break;
if (dev->num_resources) {
/* Device has resources, use them. */
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (res == NULL)
return -ENOMEM;
port->mapbase = res->start;
for (i = 0; i < ARRAY_SIZE(sci_port->irqs); ++i)
sci_port->irqs[i] = platform_get_irq(dev, i);
/* The SCI generates several interrupts. They can be muxed
* together or connected to different interrupt lines. In the
* muxed case only one interrupt resource is specified. In the
* non-muxed case three or four interrupt resources are
* specified, as the BRI interrupt is optional.
*/
if (sci_port->irqs[0] < 0)
return -ENXIO;
if (sci_port->irqs[1] < 0) {
sci_port->irqs[1] = sci_port->irqs[0];
sci_port->irqs[2] = sci_port->irqs[0];
sci_port->irqs[3] = sci_port->irqs[0];
}
} else {
/* No resources, use old-style platform data. */
port->mapbase = p->mapbase;
for (i = 0; i < ARRAY_SIZE(sci_port->irqs); ++i)
sci_port->irqs[i] = p->irqs[i] ? p->irqs[i] : -ENXIO;
}
if (p->regtype == SCIx_PROBE_REGTYPE) {
@ -2188,7 +2143,52 @@ static int sci_init_single(struct platform_device *dev,
return ret;
}
if (dev) {
switch (p->type) {
case PORT_SCIFB:
port->fifosize = 256;
sci_port->overrun_bit = 9;
sampling_rate = 16;
break;
case PORT_HSCIF:
port->fifosize = 128;
sampling_rate = 0;
sci_port->overrun_bit = 0;
break;
case PORT_SCIFA:
port->fifosize = 64;
sci_port->overrun_bit = 9;
sampling_rate = 16;
break;
case PORT_SCIF:
port->fifosize = 16;
if (p->regtype == SCIx_SH7705_SCIF_REGTYPE) {
sci_port->overrun_bit = 9;
sampling_rate = 16;
} else {
sci_port->overrun_bit = 0;
sampling_rate = 32;
}
break;
default:
port->fifosize = 1;
sci_port->overrun_bit = 5;
sampling_rate = 32;
break;
}
/* Set the sampling rate if the baud rate calculation algorithm isn't
* specified.
*/
if (p->scbrr_algo_id == SCBRR_ALGO_NONE) {
/* SCIFA on sh7723 and sh7724 need a custom sampling rate that
* doesn't match the SoC datasheet, this should be investigated.
* Let platform data override the sampling rate for now.
*/
sci_port->sampling_rate = p->sampling_rate ? p->sampling_rate
: sampling_rate;
}
if (!early) {
sci_port->iclk = clk_get(&dev->dev, "sci_ick");
if (IS_ERR(sci_port->iclk)) {
sci_port->iclk = clk_get(&dev->dev, "peripheral_clk");
@ -2208,8 +2208,6 @@ static int sci_init_single(struct platform_device *dev,
port->dev = &dev->dev;
sci_init_gpios(sci_port);
pm_runtime_enable(&dev->dev);
}
@ -2220,32 +2218,22 @@ static int sci_init_single(struct platform_device *dev,
/*
* Establish some sensible defaults for the error detection.
*/
if (!p->error_mask)
p->error_mask = (p->type == PORT_SCI) ?
sci_port->error_mask = (p->type == PORT_SCI) ?
SCI_DEFAULT_ERROR_MASK : SCIF_DEFAULT_ERROR_MASK;
/*
* Establish sensible defaults for the overrun detection, unless
* the part has explicitly disabled support for it.
*/
if (p->overrun_bit != SCIx_NOT_SUPPORTED) {
if (p->type == PORT_SCI)
p->overrun_bit = 5;
else if (p->scbrr_algo_id == SCBRR_ALGO_4)
p->overrun_bit = 9;
else
p->overrun_bit = 0;
/*
* Make the error mask inclusive of overrun detection, if
* supported.
*/
p->error_mask |= (1 << p->overrun_bit);
}
/*
* Make the error mask inclusive of overrun detection, if
* supported.
*/
sci_port->error_mask |= 1 << sci_port->overrun_bit;
port->mapbase = p->mapbase;
port->type = p->type;
port->flags = p->flags;
port->flags = UPF_FIXED_PORT | p->flags;
port->regshift = p->regshift;
/*
@ -2255,7 +2243,7 @@ static int sci_init_single(struct platform_device *dev,
*
* For the muxed case there's nothing more to do.
*/
port->irq = p->irqs[SCIx_RXI_IRQ];
port->irq = sci_port->irqs[SCIx_RXI_IRQ];
port->irqflags = 0;
port->serial_in = sci_serial_in;
@ -2270,8 +2258,6 @@ static int sci_init_single(struct platform_device *dev,
static void sci_cleanup_single(struct sci_port *port)
{
sci_free_gpios(port);
clk_put(port->iclk);
clk_put(port->fclk);
@ -2387,7 +2373,7 @@ static int sci_probe_earlyprintk(struct platform_device *pdev)
early_serial_console.index = pdev->id;
sci_init_single(NULL, &sci_ports[pdev->id], pdev->id, cfg);
sci_init_single(pdev, &sci_ports[pdev->id], pdev->id, cfg, true);
serial_console_setup(&early_serial_console, early_serial_buf);
@ -2454,7 +2440,7 @@ static int sci_probe_single(struct platform_device *dev,
return -EINVAL;
}
ret = sci_init_single(dev, sciport, index, p);
ret = sci_init_single(dev, sciport, index, p, false);
if (ret)
return ret;

View File

@ -9,7 +9,7 @@
#define SCxSR_PER(port) (((port)->type == PORT_SCI) ? SCI_PER : SCIF_PER)
#define SCxSR_BRK(port) (((port)->type == PORT_SCI) ? 0x00 : SCIF_BRK)
#define SCxSR_ERRORS(port) (to_sci_port(port)->cfg->error_mask)
#define SCxSR_ERRORS(port) (to_sci_port(port)->error_mask)
#if defined(CONFIG_CPU_SUBTYPE_SH7705) || \
defined(CONFIG_CPU_SUBTYPE_SH7720) || \

View File

@ -11,11 +11,11 @@
#define SCIx_NOT_SUPPORTED (-1)
enum {
SCBRR_ALGO_1, /* ((clk + 16 * bps) / (16 * bps) - 1) */
SCBRR_ALGO_2, /* ((clk + 16 * bps) / (32 * bps) - 1) */
SCBRR_ALGO_3, /* (((clk * 2) + 16 * bps) / (16 * bps) - 1) */
SCBRR_ALGO_4, /* (((clk * 2) + 16 * bps) / (32 * bps) - 1) */
SCBRR_ALGO_5, /* (((clk * 1000 / 32) / bps) - 1) */
SCBRR_ALGO_NONE, /* Compute sampling rate in the driver */
SCBRR_ALGO_1, /* clk / (16 * bps) */
SCBRR_ALGO_2, /* DIV_ROUND_CLOSEST(clk, 32 * bps) - 1 */
SCBRR_ALGO_3, /* clk / (8 * bps) */
SCBRR_ALGO_4, /* DIV_ROUND_CLOSEST(clk, 16 * bps) - 1 */
SCBRR_ALGO_6, /* HSCIF variable sample rate algorithm */
};
@ -70,17 +70,6 @@ enum {
SCIx_MUX_IRQ = SCIx_NR_IRQS, /* special case */
};
/* Offsets into the sci_port->gpios array */
enum {
SCIx_SCK,
SCIx_RXD,
SCIx_TXD,
SCIx_CTS,
SCIx_RTS,
SCIx_NR_FNS,
};
enum {
SCIx_PROBE_REGTYPE,
@ -108,10 +97,10 @@ enum {
}
#define SCIx_IRQ_IS_MUXED(port) \
((port)->cfg->irqs[SCIx_ERI_IRQ] == \
(port)->cfg->irqs[SCIx_RXI_IRQ]) || \
((port)->cfg->irqs[SCIx_ERI_IRQ] && \
!(port)->cfg->irqs[SCIx_RXI_IRQ])
((port)->irqs[SCIx_ERI_IRQ] == \
(port)->irqs[SCIx_RXI_IRQ]) || \
((port)->irqs[SCIx_ERI_IRQ] && \
((port)->irqs[SCIx_RXI_IRQ] < 0))
/*
* SCI register subset common for all port types.
* Not all registers will exist on all parts.
@ -142,20 +131,17 @@ struct plat_sci_port_ops {
struct plat_sci_port {
unsigned long mapbase; /* resource base */
unsigned int irqs[SCIx_NR_IRQS]; /* ERI, RXI, TXI, BRI */
unsigned int gpios[SCIx_NR_FNS]; /* SCK, RXD, TXD, CTS, RTS */
unsigned int type; /* SCI / SCIF / IRDA / HSCIF */
upf_t flags; /* UPF_* flags */
unsigned long capabilities; /* Port features/capabilities */
unsigned int sampling_rate;
unsigned int scbrr_algo_id; /* SCBRR calculation algo */
unsigned int scscr; /* SCSCR initialization */
/*
* Platform overrides if necessary, defaults otherwise.
*/
int overrun_bit;
unsigned int error_mask;
int port_reg;
unsigned char regshift;
unsigned char regtype;