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SubjectRe: [GIT PATCH] Serial updates
Russell King wrote:
> This update changes the following files:
>
> drivers/serial/8250.c | 54 ++++++++++++++++++++++++++++++++++++++++----------
> drivers/serial/8250.h | 3 ++
> 2 files changed, 47 insertions(+), 10 deletions(-)
>
> through these changes:
>
> From: Russell King: Thu Jun 23 15:05:41 BST 2005
>
> [PATCH] Serial: Mobility's 16550A ports need a helping hand
>
> The Mobility 16550A serial ports don't behave the same as standard
> 16550A ports, and need a helping hand to get them going once the
> transmitter has drained and been disabled.
>
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
>
> From: Russell King: Thu Jun 23 10:43:04 BST 2005
>
> [PATCH] Serial: Convert 8250 revision-based bug fixes to bug bitmask
>
> For some 8250 port types, we used to check the type of the port, and
> then determine whether the chip revision means the device is buggy.
> Instead, introduce a bit array, and set the appropriate bit(s) when
> we discover a buggy device.
>
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
>
> Index: drivers/serial/8250.c
> ===================================================================
> --- 06cba21e92755bf6b815221d5124ca0f9faf7985/drivers/serial/8250.c (mode:100644)
> +++ ba48375ac5262a8587eb6237134ed0aa57e7174a/drivers/serial/8250.c (mode:100644)
> @@ -132,9 +132,9 @@
> struct uart_port port;
> struct timer_list timer; /* "no irq" timer */
> struct list_head list; /* ports on this IRQ */
> - unsigned int capabilities; /* port capabilities */
> + unsigned short capabilities; /* port capabilities */
> + unsigned short bugs; /* port bugs */
> unsigned int tx_loadsz; /* transmit fifo load size */
> - unsigned short rev;
> unsigned char acr;
> unsigned char ier;
> unsigned char lcr;
> @@ -560,7 +560,14 @@
> if (id1 == 0x16 && id2 == 0xC9 &&
> (id3 == 0x50 || id3 == 0x52 || id3 == 0x54)) {
> up->port.type = PORT_16C950;
> - up->rev = rev | (id3 << 8);
> +
> + /*
> + * Enable work around for the Oxford Semiconductor 952 rev B
> + * chip which causes it to seriously miscalculate baud rates
> + * when DLL is 0.
> + */
> + if (id3 == 0x52 && rev == 0x01)
> + up->bugs |= UART_BUG_QUOT;
> return;
> }
>
> @@ -577,8 +584,6 @@
>
> id2 = id1 >> 8;
> if (id2 == 0x10 || id2 == 0x12 || id2 == 0x14) {
> - if (id2 == 0x10)
> - up->rev = id1 & 255;
> up->port.type = PORT_16850;
> return;
> }
> @@ -809,6 +814,7 @@
> // save_flags(flags); cli();
>
> up->capabilities = 0;
> + up->bugs = 0;
>
> if (!(up->port.flags & UPF_BUGGY_UART)) {
> /*
> @@ -1021,6 +1027,8 @@
> }
> }
>
> +static void transmit_chars(struct uart_8250_port *up);
> +
> static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start)
> {
> struct uart_8250_port *up = (struct uart_8250_port *)port;
> @@ -1028,6 +1036,14 @@
> if (!(up->ier & UART_IER_THRI)) {
> up->ier |= UART_IER_THRI;
> serial_out(up, UART_IER, up->ier);
> +
> + if (up->capabilities & UART_BUG_TXEN) {

Shouldn't this be up->bugs?

> + unsigned char lsr, iir;
> + lsr = serial_in(up, UART_LSR);
> + iir = serial_in(up, UART_IIR);
> + if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT)
> + transmit_chars(up);
> + }
> }
> /*
> * We only do this from uart_start
> @@ -1433,6 +1449,7 @@
> {
> struct uart_8250_port *up = (struct uart_8250_port *)port;
> unsigned long flags;
> + unsigned char lsr, iir;
> int retval;
>
> up->capabilities = uart_config[up->port.type].flags;
> @@ -1536,6 +1553,26 @@
> up->port.mctrl |= TIOCM_OUT2;
>
> serial8250_set_mctrl(&up->port, up->port.mctrl);
> +
> + /*
> + * Do a quick test to see if we receive an
> + * interrupt when we enable the TX irq.
> + */
> + serial_outp(up, UART_IER, UART_IER_THRI);
> + lsr = serial_in(up, UART_LSR);
> + iir = serial_in(up, UART_IIR);
> + serial_outp(up, UART_IER, 0);
> +
> + if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) {
> + if (!(up->capabilities & UART_BUG_TXEN)) {
> + up->capabilities |= UART_BUG_TXEN;
> + pr_debug("ttyS%d - enabling bad tx status workarounds\n",
> + port->line);
> + }
> + } else {
> + up->capabilities &= ~UART_BUG_TXEN;

ditto

> + }
> +
> spin_unlock_irqrestore(&up->port.lock, flags);
>
> /*
> @@ -1677,12 +1714,9 @@
> quot = serial8250_get_divisor(port, baud);
>
> /*
> - * Work around a bug in the Oxford Semiconductor 952 rev B
> - * chip which causes it to seriously miscalculate baud rates
> - * when DLL is 0.
> + * Oxford Semi 952 rev B workaround
> */
> - if ((quot & 0xff) == 0 && up->port.type == PORT_16C950 &&
> - up->rev == 0x5201)
> + if (up->bugs & UART_BUG_QUOT && (quot & 0xff) == 0)
> quot ++;
>
> if (up->capabilities & UART_CAP_FIFO && up->port.fifosize > 1) {
> Index: drivers/serial/8250.h
> ===================================================================
> --- 06cba21e92755bf6b815221d5124ca0f9faf7985/drivers/serial/8250.h (mode:100644)
> +++ ba48375ac5262a8587eb6237134ed0aa57e7174a/drivers/serial/8250.h (mode:100644)
> @@ -51,6 +51,9 @@
> #define UART_CAP_AFE (1 << 11) /* MCR-based hw flow control */
> #define UART_CAP_UUE (1 << 12) /* UART needs IER bit 6 set (Xscale) */
>
> +#define UART_BUG_QUOT (1 << 0) /* UART has buggy quot LSB */
> +#define UART_BUG_TXEN (1 << 1) /* UART has buggy TX IIR status */
> +
> #if defined(__i386__) && (defined(CONFIG_M386) || defined(CONFIG_M486))
> #define _INLINE_ inline
> #else
> -
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