linux/drivers/tty/serial/sh-sci.c, branch v3.9

TTY: switch tty_flip_buffer_push

2013-01-16T06:30:15Z

Now, we start converting tty buffer functions to actually use tty_port. This will allow us to get rid of the need of tty in many call sites. Only tty_port will needed and hence no more tty_port_tty_get in those paths. Now, the one where most of tty_port_tty_get gets removed: tty_flip_buffer_push. IOW we also closed all the races in drivers not using tty_port_tty_get at all yet. Also we move tty_flip_buffer_push declaration from include/linux/tty.h to include/linux/tty_flip.h to all others while we are changing it anyway. Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_insert_flip_char

2013-01-16T06:21:36Z

Now, we start converting tty buffer functions to actually use tty_port. This will allow us to get rid of the need of tty in many call sites. Only tty_port will needed and hence no more tty_port_tty_get in those paths. tty_insert_flip_char is the next one to proceed. This one is used all over the code, so the patch is huge. Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_buffer_request_room to tty_port

2013-01-16T06:17:28Z

Now, we start converting tty buffer functions to actually use tty_port. This will allow us to get rid of the need of tty pointer in many call sites. Only tty_port will be needed and hence no more tty_port_tty_get calls in those paths. Here we start with tty_buffer_request_room. Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

tty: remove use of __devinit

2012-11-21T23:22:52Z

CONFIG_HOTPLUG is going away as an option so __devinit is no longer needed. Signed-off-by: Bill Pemberton Cc: Jiri Slaby Cc: Alan Cox Cc: Lucas Tavares Cc: "David S. Miller" Cc: Peter Korsgaard Cc: Tony Prisk Acked-by: Tobias Klauser Acked-by: Nicolas Ferre Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: fix possible race cases on SCSCR register accesses

2012-11-16T02:02:51Z

In the previous commit, console write function (serial_console_write) is changed to disable SCI interrupts while printing console strings. This introduces possible race cases in the serial startup / shutdown functions on SMP systems. This patch fixes the sh-sci in the same way as commit 9ec1882df2 (tty: serial: imx: console write routing is unsafe on SMP, from Xinyu Chen , 2012-08-27) did. There could be several consumers of the console, * the kernel printk * the init process using /dev/kmsg to call printk to show log * shell, which opens /dev/console and writes with sys_write() The shell goes into the normal UART open() and write() system calls, while the other two go into the console operations. The open() call invokes serial startup function (sci_startup), which will write to the SCSCR register (to enable or disable SCI interrupts) without any locking. This will conflict with the console serial function. Add spinlock protections in sci_startup() and sci_shutdown() properly. Signed-off-by: Shinya Kuribayashi Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: add locking to console write function to avoid SMP lockup

2012-11-16T02:02:51Z

Symptom: When entering the suspend with Android logcat running, printk() call gets stuck and never returns. The issue can be observed at printk()s on nonboot CPUs when going to offline with their interrupts disabled, and never seen at boot CPU (core0 in our case). Details: serial_console_write() lacks of appropriate spinlock handling. In SMP systems, as long as sci_transmit_chars() is being processed at one CPU core, serial_console_write() can stuck at the other CPU core(s), when it tries to access to the same serial port _without_ a proper locking. serial_console_write() waits for the transmit FIFO getting empty, while sci_transmit_chars() writes data to the FIFO. In general, peripheral interrupts are routed to boot CPU (core0) by Linux ARM standard affinity settings. SCI(F) interrupts are handled by core0, so sci_transmit_chars() is processed on core0 as well. When logcat is running, it writes enormous log data to the kernel at every moment, forever. So core0 can repeatedly continue to process sci_transmit_chars() in its interrupt handler, which eventually makes the other CPU core(s) stuck at serial_console_write(). Looking at serial/8250.c, this is a known console write lockup issue with SMP kernels. Fix the sh-sci driver in the same way 8250.c does. Signed-off-by: Shinya Kuribayashi Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: fix common SCIFB regmap definition

2012-11-16T02:02:51Z

About FIFO count, there are two variants of SCIFs which show a) TX count in upper, RX count in lower byte of FDR register b) TX count in TFDR register, RX count in RFDR register Common SCIFB regmap in current source code is defined as "a". At least 7372 and 73a0 HW manual say their SICFB are "b". This patch alters the definition to "b", considering the current one has come from a mistake. The reason is as follows. The flag SCIFB sh-sci driver means it has 256 byte FIFO. The count is from 0(empty) to 256(full), that makes 9-bit. Because FDR is 16-bit register, it can not hold two 9-bits. That's why, SCIFB can not be "a". Signed-off-by: Takashi Yoshii Signed-off-by: Shinya Kuribayashi Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: mask SCTFDR/RFDR according to fifosize

2012-11-16T02:02:37Z

Current mask 0xff to SCTFDR/RFDR damages SCIFB, because the registers on SCIFB have 9-bit data (0 to 256). This patch changes the mask according to port->fifosize. Though I'm not sure if the mask is really needed (I don't know if there are variants which have non-zero upper bits), it is safer. Signed-off-by: Takashi Yoshii Signed-off-by: Shinya Kuribayashi Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: support lower baud rate

2012-11-16T02:02:37Z

Support prescaler 1/16 and 1/64, in addition to current 1 and 1/4. Supporting below 2400bps was dropped long time ago in mainline. Since then, setting lower rate has been resulting in erroneous register value, without indicating any errors through API. This patch adds more prescaler to support lower rates again. This still doesn't check range, but we won't hit the case because even 50bps at 48MHz clock is now supported. Signed-off-by: Takashi Yoshii Signed-off-by: Shinya Kuribayashi Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: fix condition test to set SCBRR

2012-11-16T02:02:37Z

SCBRR == 0 is valid value (divide by 1). Signed-off-by: Takashi Yoshii Signed-off-by: Shinya Kuribayashi Signed-off-by: Greg Kroah-Hartman