BMC/Intel-BMC/linux.git/drivers/tty/serial/max310x.c, branch dev-5.3

Merge 5.2-rc3 into tty-next

2019-06-03T11:53:20+00:00

We want the tty/serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman

tty: max310x: Fix external crystal register setup

2019-05-21T10:18:17+00:00

The datasheet states: Bit 4: ClockEnSet the ClockEn bit high to enable an external clocking (crystal or clock generator at XIN). Set the ClockEn bit to 0 to disable clocking Bit 1: CrystalEnSet the CrystalEn bit high to enable the crystal oscillator. When using an external clock source at XIN, CrystalEn must be set low. The bit 4, MAX310X_CLKSRC_EXTCLK_BIT, should be set and was not. This was required to make the MAX3107 with an external crystal on our board able to send or receive data. Signed-off-by: Joe Burmeister Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: max310x: Split uart characters insertion loop

2019-05-21T10:15:54+00:00

Batch read mode doesn't check any conditions or flags except the Rx overflow one. But it may only happen after the last character is pushed into the RHR register. In this case we shouldn't push all the read characters with overrun flag set, but only the last one caused the FIFO overflow. This commit splits the characters retrieval loop into two parts. First one is ordinary intsert-chars procedure without taking the overrun status into account. Second part inserts the last character checking whether the overrun happened and pushing a '\0' character with TTY_OVERRUN flag to a flip-buffer. If we left the loop the way it was the '\0' character would be inserted after each character retrieved at the overrun occasion. Signed-off-by: Serge Semin Signed-off-by: Greg Kroah-Hartman

tty: max310x: Optionally enable rs485 on startup

2019-05-21T10:15:53+00:00

UART port might be pre-configured with rs485 enabled flag at the time of the port starting up process. In this case we need to have the hardware rs485-related registers initialized in accordance with the rs485 flags and settings provided by the configs descriptor. Signed-off-by: Serge Semin Signed-off-by: Greg Kroah-Hartman

tty: max310x: Add rx-during-tx rs485 flag support

2019-05-21T10:15:53+00:00

The driver currently sets the echo suppression bit by default when rs485 is enabled. Naturally it disables any data retrieval in rs485 mode while RTSn is pushed up. The receiver gate (RX_) can be enabled just by clearing (or not setting) the EchoSuprs bit of mode2 register. So by setting or clearing the bit we implement the SER_RS485_RX_DURING_TX rs485 flag support. Signed-off-by: Serge Semin Signed-off-by: Greg Kroah-Hartman

tty: max310x: Fix invalid baudrate divisors calculator

2019-05-21T10:15:53+00:00

Current calculator doesn't do it' job quite correct. First of all the max310x baud-rates generator supports the divisor being less than 16. In this case the x2/x4 modes can be used to double or quadruple the reference frequency. But the current baud-rate setter function just filters all these modes out by the first condition and setups these modes only if there is a clocks-baud division remainder. The former doesn't seem right at all, since enabling the x2/x4 modes causes the line noise tolerance reduction and should be only used as a last resort to enable a requested too high baud-rate. Finally the fraction is supposed to be calculated from D = Fref/(c*baud) formulae, but not from D % 16, which causes the precision loss. So to speak the current baud-rate calculator code works well only if the baud perfectly fits to the uart reference input frequency. Lets fix the calculator by implementing the algo fully compliant with the fractional baud-rate generator described in the datasheet: D = Fref / (c*baud), where c={16,8,4} is the x1/x2/x4 rate mode respectively, Fref - reference input frequency. The divisor fraction is calculated from the same formulae, but making sure it is found with a resolution of 0.0625 (four bits). Signed-off-by: Serge Semin Signed-off-by: Greg Kroah-Hartman

tty: max310x: Don't pass stacked buffers to SPI

2019-05-21T10:15:53+00:00

SPI transfer tx/rx buffers must be DMA-safe and the structure documentation clearly states this. Data declared on the system stack isn't DMA-safe [1]. Instead at least kernel memory should be used for the buffers. In order to fix this here we can create the buffers at the device probing stage and use them without any synchronization, since batch read/write methods are called from non-reentrant contexts - either from rx-event IRQ threaded handler or from the tx workqueue item. [1] Documentation/DMA-API-HOWTO.txt Signed-off-by: Serge Semin Signed-off-by: Greg Kroah-Hartman

tty: max310x: Introduce max310x_one port macro-wrapper

2019-05-21T10:15:53+00:00

uart_port structure instance is embedded into the max310x_one super-structure, which is accessed by some of the uart-port callback methods. In order to improve the callback's code readability lets define the to_max310x_port() wrapper which just translates the passed uart_port pointer to the max310x_one one. It is also going to be handy in future commits. Signed-off-by: Serge Semin Signed-off-by: Greg Kroah-Hartman

tty: max310x: Simplify tx-work item code

2019-05-21T10:15:53+00:00

Since cmwq introduction in the kernel, workqueues've been turned into non-reentrant execution contexts [1]. It means any work item is guaranteed to be executed by at most one worker system-wide at any given time. Since tx-handler max310x_handle_tx() is called by a single work item we don't need it to be self-protected by the mutex. We also don't need to check the tx work item pending state before scheduling it (which in the first place was racy btw), since cmwq will make sure to reschedule the item if it wasn't pending at the moment of schedule_work() call. [1] Documentation/core-api/workqueue.rst Signed-off-by: Serge Semin Signed-off-by: Greg Kroah-Hartman

serial: max310x: Fix to avoid potential NULL pointer dereference

2019-03-19T14:37:43+00:00

of_match_device can return a NULL pointer when matching device is not found. This patch avoids a scenario causing NULL pointer derefernce. Signed-off-by: Aditya Pakki Cc: stable Signed-off-by: Greg Kroah-Hartman