[PATCH 5/6] sdio_uart: Use kfifo instead of the messy circ stuff

Alan Cox
2009-11-02T16:59:40Z

Probably all the tty code should switch to this, especially when the new
lockless kfifo is merged.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---

drivers/mmc/card/sdio_uart.c | 86 +++++++++++++-----------------------------
1 files changed, 27 insertions(+), 59 deletions(-)

diff --git a/drivers/mmc/card/sdio_uart.c b/drivers/mmc/card/sdio_uart.c
index e611bc6..c4fc27d 100644
--- a/drivers/mmc/card/sdio_uart.c
+++ b/drivers/mmc/card/sdio_uart.c
@@ -32,7 +32,7 @@
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include <linux/serial_reg.h>
-#include <linux/circ_buf.h>
+#include <linux/kfifo.h>
#include <linux/gfp.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
@@ -46,18 +46,9 @@
#define UART_NR 8 /* Number of UARTs this driver can handle */

-#define UART_XMIT_SIZE PAGE_SIZE
+#define FIFO_SIZE PAGE_SIZE
#define WAKEUP_CHARS 256

-#define circ_empty(circ) ((circ)->head == (circ)->tail)
-#define circ_clear(circ) ((circ)->head = (circ)->tail = 0)
-
-#define circ_chars_pending(circ) \
- (CIRC_CNT((circ)->head, (circ)->tail, UART_XMIT_SIZE))
-
-#define circ_chars_free(circ) \
- (CIRC_SPACE((circ)->head, (circ)->tail, UART_XMIT_SIZE))
-

struct uart_icount {
__u32 cts;
@@ -82,7 +73,7 @@ struct sdio_uart_port {
struct mutex func_lock;
struct task_struct *in_sdio_uart_irq;
unsigned int regs_offset;
- struct circ_buf xmit;
+ struct kfifo *xmit_fifo;
spinlock_t write_lock;
struct uart_icount icount;
unsigned int uartclk;
@@ -104,6 +95,9 @@ static int sdio_uart_add_port(struct sdio_uart_port *port)
kref_init(&port->kref);
mutex_init(&port->func_lock);
spin_lock_init(&port->write_lock);
+ port->xmit_fifo = kfifo_alloc(FIFO_SIZE, GFP_KERNEL, &port->write_lock);
+ if (port->xmit_fifo == NULL)
+ return -ENOMEM;

spin_lock(&sdio_uart_table_lock);
for (index = 0; index < UART_NR; index++) {
@@ -453,9 +447,11 @@ static void sdio_uart_receive_chars(struct sdio_uart_port *port,

static void sdio_uart_transmit_chars(struct sdio_uart_port *port)
{
- struct circ_buf *xmit = &port->xmit;
+ struct kfifo *xmit = port->xmit_fifo;
int count;
struct tty_struct *tty;
+ u8 iobuf[16];
+ int len;

if (port->x_char) {
sdio_out(port, UART_TX, port->x_char);
@@ -466,24 +462,21 @@ static void sdio_uart_transmit_chars(struct sdio_uart_port *port)

tty = tty_port_tty_get(&port->port);

- if (tty == NULL || circ_empty(xmit) || tty->stopped || tty->hw_stopped) {
+ if (tty == NULL || !kfifo_len(xmit) || tty->stopped || tty->hw_stopped) {
sdio_uart_stop_tx(port);
return;
}

- count = 16;
- do {
- sdio_out(port, UART_TX, xmit->buf[xmit->tail]);
- xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+ len = kfifo_get(xmit, iobuf, 16);
+ for (count = 0; count < len; count++) {
+ sdio_out(port, UART_TX, iobuf[count]);
port->icount.tx++;
- if (circ_empty(xmit))
- break;
- } while (--count > 0);
+ }

- if (circ_chars_pending(xmit) < WAKEUP_CHARS)
+ if (len < WAKEUP_CHARS)
tty_wakeup(tty);

- if (circ_empty(xmit))
+ if (len == 0)
sdio_uart_stop_tx(port);
tty_kref_put(tty);
}
@@ -606,22 +599,17 @@ static int sdio_uart_activate(struct tty_port *tport, struct tty_struct *tty)
*/
set_bit(TTY_IO_ERROR, &tty->flags);

- /* Initialise and allocate the transmit buffer. */
- page = __get_free_page(GFP_KERNEL);
- if (!page)
- return -ENOMEM;
- port->xmit.buf = (unsigned char *)page;
- circ_clear(&port->xmit);
+ kfifo_reset(port->xmit_fifo);

ret = sdio_uart_claim_func(port);
if (ret)
- goto err1;
+ return ret;
ret = sdio_enable_func(port->func);
if (ret)
- goto err2;
+ goto err1;
ret = sdio_claim_irq(port->func, sdio_uart_irq);
if (ret)
- goto err3;
+ goto err2;

/*
* Clear the FIFO buffers and disable them.
@@ -665,12 +653,10 @@ static int sdio_uart_activate(struct tty_port *tport, struct tty_struct *tty)
sdio_uart_release_func(port);
return 0;

-err3:
- sdio_disable_func(port->func);
err2:
- sdio_uart_release_func(port);
+ sdio_disable_func(port->func);
err1:
- free_page((unsigned long)port->xmit.buf);
+ sdio_uart_release_func(port);
return ret;
}

@@ -693,7 +679,7 @@ static void sdio_uart_shutdown(struct tty_port *tport)

ret = sdio_uart_claim_func(port);
if (ret)
- goto skip;
+ return ret;

sdio_uart_stop_rx(port);

@@ -715,10 +701,6 @@ static void sdio_uart_shutdown(struct tty_port *tport)
sdio_disable_func(port->func);

sdio_uart_release_func(port);
-
-skip:
- /* Free the transmit buffer page. */
- free_page((unsigned long)port->xmit.buf);
}

/**
@@ -789,26 +771,12 @@ static int sdio_uart_write(struct tty_struct * tty, const unsigned char *buf,
int count)
{
struct sdio_uart_port *port = tty->driver_data;
- struct circ_buf *circ = &port->xmit;
- int c, ret = 0;
+ int ret;

if (!port->func)
return -ENODEV;

- spin_lock(&port->write_lock);
- while (1) {
- c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
- if (count < c)
- c = count;
- if (c <= 0)
- break;
- memcpy(circ->buf + circ->head, buf, c);
- circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
- buf += c;
- count -= c;
- ret += c;
- }
- spin_unlock(&port->write_lock);
+ ret = kfifo_put(port->xmit_fifo, buf, count);

if ( !(port->ier & UART_IER_THRI)) {
int err = sdio_uart_claim_func(port);
@@ -826,13 +794,13 @@ static int sdio_uart_write(struct tty_struct * tty, const unsigned char *buf,
static int sdio_uart_write_room(struct tty_struct *tty)
{
struct sdio_uart_port *port = tty->driver_data;
- return port ? circ_chars_free(&port->xmit) : 0;
+ return FIFO_SIZE - kfifo_len(port->xmit_fifo);
}

static int sdio_uart_chars_in_buffer(struct tty_struct *tty)
{
struct sdio_uart_port *port = tty->driver_data;
- return port ? circ_chars_pending(&port->xmit) : 0;
+ return kfifo_len(port->xmit_fifo);
}

static void sdio_uart_send_xchar(struct tty_struct *tty, char ch)