- 06 Nov, 2014 40 commits
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Fabian Frederick authored
Use container_of instead of casting first structure member. Signed-off-by:
Fabian Frederick <fabf@skynet.be> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Sebastian Andrzej Siewior authored
This patch adds the required pieces to 8250-OMAP UART driver for DMA support. The TX burst size is set to 1 so we can send an arbitrary amount of bytes. The RX burst is currently set to 48 which means we receive an DMA interrupt every 48 bytes and have to reprogram everything. Less bytes in the RX-FIFO mean that no DMA transfer will happen and the UART will send a RX-timeout _or_ RDI event at which point the FIFO will be manually purged. There is a workaround for TX-DMA on AM33xx where we put the first byte into the FIFO to kick start the DMA process. Haven't seen this problem on OMAP36xx (beagle board xm) or DRA7xx. On AM375x there is "Usage Note 2.7: UART: Cannot Acknowledge Idle Requests in Smartidle Mode When Configured for DMA Operations" in the errata document. This problem persists even after disabling DMA in the UART and will be addressed in the HWMOD. v10: - delay update_registers() from set_termios() until TX-DMA is done. It has been reported / proved that invoking update_registers() while TX-DMA is in progress may stall the DMA operation and it won't finish. - use the new omap DMA-TX-RX hooks and DMA only interrupt routine. Signed-off-by:
Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by:
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Sebastian Andrzej Siewior authored
We have (or will have) custom DMA callbacks in the omap driver due to the different behaviour in the RX and TX case. To make this work we need a few changes in the IRQ handler to invoke the rx_handler again after the "manual" mode or retry the tx_handler again before falling back to the manual mode. Heikki didn't want to see the extra hacks in the generic / default irq handler and Peter wasn't too happy about an OMAP-only IRQ handler. The way I planned it is to use this extra IRQ routine only in DMA case. If Peter dislike this approach then I hope Heikki doesn't block changes in the default IRQ handler :) Signed-off-by:
Heikki Krogerus <heikki.krogerus@linux.intel.com> Reviewed-by:
Peter Hurley <peter@hurleysoftware.com> Signed-off-by:
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Sebastian Andrzej Siewior authored
The omap needs a DMA request pending right away. If it is enqueued once the bytes are in the FIFO then nothing will happen and the FIFO will be later purged via RX-timeout interrupt. This patch enqueues RX-DMA request on completion but not if it was aborted on error. The first enqueue will happen in the driver in startup. Signed-off-by:
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Sebastian Andrzej Siewior authored
This patch provides mostly a copy of serial8250_tx_dma() + __dma_tx_complete() with the following extensions: - DMA bug At least on AM335x the following problem exists: Even if the TX FIFO is empty and a TX transfer is programmed (and started) the UART does not trigger the DMA transfer. After $TRESHOLD number of bytes have been written to the FIFO manually the UART reevaluates the whole situation and decides that now there is enough room in the FIFO and so the transfer begins. This problem has not been seen on DRA7 or beagle board xm (OMAP3). I am not sure if this is UART-IP core specific or DMA engine. The workaround is to use a threshold of one byte, program the DMA transfer minus one byte and then to put the first byte into the FIFO to kick start the transfer. - support for runtime PM RPM is enabled on start_tx(). We can't disable RPM on DMA complete callback because there is still data in the FIFO which is being sent. We have to wait until the FIFO is empty before we disable it. For this to happen we fake a TX sent error and enable THRI. Once the FIFO is empty we receive an interrupt and since the TTY-buffer is still empty we "put RPM" via __stop_tx(). Should it been filed then in the start_tx() path we should program the DMA transfer and remove the error flag and the THRI bit. Signed-off-by:
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Sebastian Andrzej Siewior authored
The OMAP has a few corner cases where it needs a share of kindness of affection to do the right thing. Heikki Krogerus suggested that instead adding the quirks into the default DMA implementation, OMAP could get its own copy of the function. And Alan suggested the same thing so here we go. This patch provides callbacks for custom TX/RX DMA implementation. If there are not setup / used, then the default (current) implementation is used. Signed-off-by:
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Sebastian Andrzej Siewior authored
After dmaengine_terminate_all() has been invoked then both DMA drivers (edma and omap-dma) do not invoke dma_cookie_complete() to mark the transfer as complete. This dma_cookie_complete() is performed by the Synopsys DesignWare driver which is probably the only one that is used by omap8250-dma and hence don't see following problem… …which is that once a RX transfer has been terminated then following query of channel status reports DMA_IN_PROGRESS (again: the actual transfer has been canceled, there is nothing going on anymore). This means that serial8250_rx_dma() never enqueues another DMA transfer because it (wrongly) assumes that there is a transer already pending. Vinod Koul refuses to accept a patch which adds this dma_cookie_complete() to both drivers and so dmaengine_tx_status() would report DMA_COMPLETE instead (and behave like the Synopsys DesignWare driver already does). He argues that I am not allowed to use the cookie to query the status and that the driver already cleaned everything up after the invokation of dmaengine_terminate_all(). To end this I add a bookkeeping whether or not a RX-transfer has been started to the 8250-dma code. It has already been done for the TX side. *Now* we learn about the RX status based on our bookkeeping and don't need dmaengine_tx_status() for this anymore. Cc: vinod.koul@intel.com Reviewed-by:
Tony Lindgren <tony@atomide.com> Tested-by:
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Sebastian Andrzej Siewior authored
Right now it is possible that serial8250_tx_dma() fails and returns -EBUSY. The caller (serial8250_start_tx()) will then enable UART_IER_THRI which will generate an interrupt once the TX FIFO is empty. In serial8250_handle_irq() nothing will happen because up->dma is set and so serial8250_tx_chars() won't be invoked. We end up with plenty of interrupts and some "too much work for irq" output. This patch introduces dma_tx_err in struct uart_8250_port to signal that the last invocation of serial8250_tx_dma() failed so we can fill the TX FIFO manually. Should the next invocation of serial8250_start_tx() succeed then the dma_tx_err flag along with the THRI bit is removed and DMA only usage may continue. Reviewed-by:
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Sebastian Andrzej Siewior authored
This patch provides a 8250-core based UART driver for the internal OMAP UART. The long term goal is to provide the same functionality as the current OMAP uart driver and DMA support. I tried to merge omap-serial code together with the 8250-core code. There should should be hardly a noticable difference. The trigger levels are different compared to omap-serial: - omap serial TX: Interrupt comes after TX FIFO has room for 16 bytes. TX of 4096 bytes in one go results in 256 interrupts RX: Interrupt comes after there is on byte in the FIFO. RX of 4096 bytes results in 4096 interrupts. - this driver TX: Interrupt comes once the TX FIFO is empty. TX of 4096 bytes results in 65 interrupts. That means there will be gaps on the line while the driver reloads the FIFO. RX: Interrupt comes once there are 48 bytes in the FIFO or less over "longer" time frame. We have 1 / 11520 * 10^3 * 16 => 1.38… ms 1.38ms to react and purge the FIFO on 115200,8N1. Since the other driver fired after each byte it had ~5.47ms time to react. This _may_ cause problems if one relies on no missing bytes and has no flow control. On the other hand we get only 85 interrupts for the same amount of data. It has been only tested as console UART on am335x-evm, dra7-evm and beagle bone. I also did some longer raw-transfers to meassure the load. The device name is ttyS based instead of ttyO. If a ttyO based node name is required please ask udev for it. If both driver are activated (this and omap-serial) then this serial driver will take control over the device due to the link order v9…v10: - Tony noticed that omap3 won't show anything after waking up from core off. In v9 I reworked the register restore and set IER to 0 by accident. This went unnoticed because start_tx usually sets ier (either due to DMA bug or due to TX-complete IRQ). - dropped EFR and SLEEP from capabilities. We do have both but nobody should touch it. We already handle SLEEP ourself. - make the private copy of the registers (like EFR) u8 instead u32 - drop MDR1 & DL[ML] reset in restore registers. Does not look required it is set to the required value later. - update MDR1 & SCR only if changed. - set MDR1 as the last thing. The errata says that we should setup everything before MDR1 set. - avoid div by 0 in omap_8250_get_divisor() if baud rate gets very large (Frans Klaver fixed the same thing omap-serial) - drop "is in early stage" from Kconfig. v8…v9: - less on a file seems to hang the am335x after a while. I believe I introduce this bug a while ago since I can reproduce this prior to v8. Fixed by redoing the omap8250_restore_regs() v7…v8: - redo the register write. There is now one function for that which is used from set_termios() and runtime-resume. - drop PORT_OMAP_16750 and move the setup to the omap file. We have our own set termios function anyway (Heikki Krogerus) - use MEM instead of MEM32. TRM of AM/DM37x says that 32bit access on THR might result in data abort. We only need 32bit access in the errata function which is before we use 8250's read function so it doesn't matter. v4…v7: - change trigger levels after some tests with raw transfers. v3…v4: - drop RS485 support - wire up ->throttle / ->unthrottle v2…v3: - wire up startup & shutdown for wakeup-irq handling. - RS485 handling (well the core does). v1…v2: - added runtime PM. Could somebody could please double check this? - added omap_8250_set_termios() Reviewed-by:Frans Klaver <frans.klaver@xsens.com> Signed-off-by:
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Sebastian Andrzej Siewior authored
if I boot with console=ttyS0 and the omap driver is module I end up with | console [ttyS0] disabled | omap8250 44e09000.serial: ttyS0 at MMIO 0x44e09000 (irq = 88, base_baud = 3000000) is a 8250 | Unable to handle kernel paging request at virtual address c07a9de0 | Modules linked in: 8250_omap(+) | CPU: 0 PID: 908 Comm: modprobe Not tainted 3.17.0-rc5+ #1593 | PC is at serial8250_console_setup+0x0/0xc8 | LR is at register_console+0x13c/0x3a4 | [<c0078788>] (register_console) from [<c02d0340>] (uart_add_one_port+0x3cc/0x420) | [<c02d0340>] (uart_add_one_port) from [<c02d38a4>] (serial8250_register_8250_port+0x298/0x39c) | [<c02d38a4>] (serial8250_register_8250_port) from [<bf006274>] (omap8250_probe+0x218/0x3dc [8250_omap]) | [<bf006274>] (omap8250_probe [8250_omap]) from [<c02e3424>] (platform_drv_probe+0x2c/0x5c) | [<c02e3424>] (platform_drv_probe) from [<c02e1eac>] (driver_probe_device+0x104/0x228) … | [<c009fa48>] (SyS_init_module) from [<c000e6e0>] (ret_fast_syscall+0x0/0x30) | Code: 7823603b f8314620 051b3013 491ed416 (44792204) because serial8250_console_setup() is already gone. Signed-off-by:
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Sebastian Andrzej Siewior authored
Frans reworded the two comments with better English for better understanding. His review hit the mailing list after the patch got applied so here is an incremental update. Reported-by:
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Janusz Uzycki authored
When using mxs-auart based console, sometime we need the sysrq function to help debugging kernel. The sysrq code is basically there, this patch just simply enable it. Signed-off-by:
Janusz Uzycki <j.uzycki@elproma.com.pl> Reviewed-by:
Fabio Estevam <fabio.estevam@freescale.com> Signed-off-by:
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Markus Pargmann authored
This error message is not necessary. The driver core code will print all probe error messages. It also resolves some error codes to proper error messages. For example -EPROBE_DEFER will only be printed as an info message. This patch removes the error message as the core prints the same information. Signed-off-by:
Markus Pargmann <mpa@pengutronix.de> Acked-by:
Felipe Balbi <balbi@ti.com> Signed-off-by:
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Peter Hurley authored
A port count mismatch occurs if mutex_lock_interruptible() exits uart_open() and the port has already been opened. This may prematurely close a port on an open tty. Since uart_close() is _always_ called if uart_open() fails, the port count must be corrected if errors occur. Always increment the port count in uart_open(), regardless of errors; always decrement the port count in uart_close(). Note that tty_port_close_start() decrements the port count when uart_open() was successful. Signed-off-by:
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Peter Hurley authored
uart_start() only claims the port->lock to call __uart_start(), which does the actual processing. Eliminate the extra acquire/release in uart_write(); call __uart_start() directly with port->lock already held. Signed-off-by:
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Peter Hurley authored
The key function of uart_add_one_port() is to cross-reference the UART driver's port structure with the serial core's state table; keep the assignments together and document this crucial association. Signed-off-by:
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Peter Hurley authored
tty_port_init() initializes close_delay and closing_wait to these same values; remove. Signed-off-by:
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Peter Hurley authored
The wrapped line looks wrong and out-of-place; leave it as >80 char line. Signed-off-by:
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Peter Hurley authored
Note the serial_struct flags for which the kernel ignores and performs no action. The flags cannot be removed since they form part of the userspace interface via the TIOCSSERIAL/TIOCGSERIAL ioctls. Signed-off-by:
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Peter Hurley authored
The userspace-defined ASYNC_* flags in include/uapi/linux/tty_flags.h are the authoritative bit definitions for the serial_struct flags, and thus for any derivative values or fields. Although the serial core provides the TIOCSSERIAL and TIOCGSERIAL ioctls to set and retrieve these flags from userspace, it defines these bits independently, as UPF_* macros. Define the UPF_* macros which are userspace-modifiable directly from the ASYNC_* symbolic constants. Add compile-time test to ensure the bits changeable by TIOCSSERIAL match the defined range in the uapi header. Add ASYNCB_MAGIC_MULTIPLIER to the uapi header since this bit is programmable by userspace. Signed-off-by:
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Peter Hurley authored
The low-level uart driver may modify termios settings to override settings that are not compatible with the uart, such as CRTSCTS. Thus, callers of the low-level uart driver's set_termios() method must hold termios_rwsem write lock to prevent concurrent access to termios, in case such override occurs. The termios_rwsem lock requirement does not extend to console setup (ie., uart_set_options), as console setup cannot race with tty operations. Nor does this lock requirement extend to functions which cannot be concurrent with tty ioctls (ie., uart_port_startup() and uart_resume_port()). Further, always claim the port mutex to protect hardware re-reprogramming in the set_termios() uart driver method. Note this is unnecessary for console initialization in uart_set_options() which cannot be concurrent with other uart operations. Signed-off-by:
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Peter Hurley authored
The tty buffers (and any line discipline buffers) must be flushed after the UART hardware has shutdown; otherwise, a racing open on the same tty may receive data from the previous session, which is a security hazard. However, holding the port mutex while flushing the line discipline buffers creates a lock inversion if the set_termios() handler takes the port mutex (as it does in the followup patch, 'serial: Fix locking for uart driver set_termios method'. Flush the ldisc buffers after dropping the port mutex; the tty lock is still held which prevents a concurrent open() from advancing while flushing. Since no new rx data is possible after uart_shutdown() until a new open reinitializes the port, the later flush has no impact on what data is being discarded. Signed-off-by:
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Peter Hurley authored
In the context of the final tty & port close, flushing the tx ring buffer after the hardware has already been shutdown and the ring buffer freed is neither required nor desirable. uart_flush_buffer() performs 3 operations: 1. Resets tx ring buffer indices, but the tx ring buffer has already been freed and the indices are reset if the port is re-opened. 2. Calls uart driver's flush_buffer() method 5 in-tree uart drivers define flush_buffer() methods: amba-pl011, atmel-serial, imx, serial-tegra, timbuart These have been refactored into the shutdown() method, if required. 3. Kicks the ldisc for more writing, but this is undesirable. The file handle is being released; any waiting writer will will be kicked out by tty_release() with a warning. Further, the N_TTY ldisc may generate SIGIO for a file handle which is no longer valid. Cc: Nicolas Ferre <nicolas.ferre@atmel.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Laxman Dewangan <ldewangan@nvidia.com> Signed-off-by: -
Peter Hurley authored
tty_ldisc_flush() first clears the line discipline input buffer, then clears the tty flip buffers. However, this allows for existing data in the tty flip buffers to be added after the ldisc input buffer has been cleared, but before the flip buffers have been cleared. Add an optional ldisc parameter to tty_buffer_flush() to allow tty_ldisc_flush() to pass the ldisc to clear. NB: Initially, the plan was to do this automatically in tty_buffer_flush(). However, an audit of the behavior of existing line disciplines showed that performing a ldisc buffer flush on ioctl(TCFLSH) was not always the outcome. For example, some line disciplines have flush_buffer() methods but not ioctl() methods, so a ->flush_buffer() command would be unexpected. Reviewed-by:
Alan Cox <alan@linux.intel.com> Signed-off-by:
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Peter Hurley authored
When changing the ldisc on one end of a pty pair, there may be waiting readers/writers on the other end which may not exit from the ldisc i/o loop, preventing tty_ldisc_lock_pair_timeout() from acquiring the other side's ldisc lock. Only acquire this side's ldisc lock; although this will no longer prevent the other side from writing new input, that input will not be processed until after the ldisc change completes. This has no effect on normal ttys; new input from the driver was never disabled. Remove tty_ldisc_enable_pair(). Reviewed-by:
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Peter Hurley authored
When hanging up one end of a pty pair, there may be waiting readers/writers on the other end which may not exit, preventing tty_ldisc_lock_pair() from acquiring the other side's ldisc lock. Only acquire this side's ldisc lock; although this will no longer prevent the other side from writing new input, that input will not be processing until after the ldisc hangup is complete. Reported-by:
Sasha Levin <sasha.levin@oracle.com> Reviewed-by:
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Peter Hurley authored
tty_ldisc_lock(), tty_ldisc_unlock(), and tty_ldisc_lock_nested() are low-level aliases for the underlying lock mechanism. Rename with double underscore to allow for new, higher level functions with those names. Reviewed-by:
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Peter Hurley authored
When releasing one end of a pty pair, that end may just have written to the other, which the input processing worker, flush_to_ldisc(), is still working on but has not completed the copy to the other end's read buffer. So input may not appear to be available to a waiting reader but yet TTY_OTHER_CLOSED is now observed. The n_tty line discipline has worked around this by waiting for input processing to complete and then re-checking if input is available before exiting with -EIO. Since the tty/ldisc lock reordering, the wait for input processing to complete can now occur during final close before setting TTY_OTHER_CLOSED. In this way, a waiting reader is guaranteed to see input available (if any) before observing TTY_OTHER_CLOSED. Reviewed-by:
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Peter Hurley authored
With the revised tty lock order and lockdep annotation, claiming the pty slave lock is now safe while still holding the pty master lock. Signed-off-by:
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Peter Hurley authored
The tty_unhangup() function is not defined. Reviewed-by:
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Peter Hurley authored
Eliminate the requirement of specifying the tty lock nesting at lock time; instead, set the lock subclass for slave ptys at pty install (normal ttys and master ptys use subclass 0). Signed-off-by:
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Peter Hurley authored
When releasing the master pty, the slave pty also needs to be locked to prevent concurrent tty count changes for the slave pty and to ensure that only one parallel master and slave release observe the final close, and proceed to destruct the pty pair. Conversely, when releasing the slave pty, locking the master pty is not necessary (since the master's state can be inferred by the slave tty count). Introduce tty_lock_slave()/tty_unlock_slave() which acquires/releases the tty lock of the slave pty. Remove tty_lock_pair()/tty_unlock_pair(). Dropping the tty_lock is no longer required to re-establish a stable lock order. Reviewed-by:
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Peter Hurley authored
The local o_tty variable in tty_release() is now accessed only when closing the pty master. Set o_tty to slave pty when closing pty master, otherwise NULL; use o_tty != NULL as replacement for pty_master. Reviewed-by:
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Peter Hurley authored
Passing the 'other' tty to tty_release_checks() only makes sense for a pty pair; make o_tty scope local instead. Reviewed-by:
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Peter Hurley authored
Passing the 'other' tty to tty_ldisc_release() only makes sense for a pty pair; make o_tty function local instead. Reviewed-by:
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Peter Hurley authored
Perform work flush for both ends of a pty pair within tty_flush_works(), rather than calling twice. Reviewed-by:
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Peter Hurley authored
When the slave side closes and its tty count is 0, the pty pair can be destroyed; the master side must have already closed for the slave side tty count to be 0. Thus, only the pty master close must check if the slave side has closed by checking the slave tty count. Remove the pre-computed closing flags and check the actual count(s). Regular ttys are unaffected by this change. Reviewed-by:
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Peter Hurley authored
Holding the tty_lock() is necessary to prevent concurrent changes to the tty count that may cause it to differ from the open file list count. The tty_lock() is already held at all call sites. NB: Note that the check for the pty master tty count is safe because the slave's tty_lock() is held while decrementing the pty master tty count. Reviewed-by:
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Peter Hurley authored
Releasing the tty locks while waiting for the tty wait queues to be empty is no longer necessary nor desirable. Prior to "tty: Don't take tty_mutex for tty count changes", dropping the tty locks was necessary to reestablish the correct lock order between tty_mutex and the tty locks. Dropping the global tty_mutex was necessary; otherwise new ttys could not have been opened while waiting. However, without needing the global tty_mutex held, the tty locks for the releasing tty can now be held through the sleep. The sanity check is for abnormal conditions caused by kernel bugs, not for recoverable errors caused by misbehaving userspace; dropping the tty locks only allows the tty state to get more sideways. Reviewed-by:
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Peter Hurley authored
Holding tty_mutex is no longer required to serialize changes to the tty_count or to prevent concurrent opens of closing ttys; tty_lock() is sufficient. Reviewed-by:
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