linux-stable.git/drivers/tty/serial, branch linux-5.18.y

tty: 8250: Add support for Brainboxes PX cards.

2022-08-17T12:42:23+00:00

[ Upstream commit ef5a03a26c87a760bc3d86b5af7b773e82f8b1b7 ]

Add support for some of the Brainboxes PCIe (PX) range of
serial cards, including the PX-101, PX-235/PX-246,
PX-203/PX-257, PX-260/PX-701, PX-310, PX-313,
PX-320/PX-324/PX-376/PX-387, PX-335/PX-346, PX-368, PX-420,
PX-803 and PX-846.

Signed-off-by: Cameron Williams 
Cc: stable 
Link: https://lore.kernel.org/r/AM5PR0202MB2564669252BDC59BF55A6E87C4879@AM5PR0202MB2564.eurprd02.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: 8250: Add proper clock handling for OxSemi PCIe devices

2022-08-17T12:42:23+00:00

[ Upstream commit 366f6c955d4d1a5125ffcd6875ead26a3c7a2a1c ]

Oxford Semiconductor PCIe (Tornado) 950 serial port devices are driven
by a fixed 62.5MHz clock input derived from the 100MHz PCI Express clock.

We currently drive the device using its default oversampling rate of 16
and the clock prescaler disabled, consequently yielding the baud base of
3906250.  This base is inadequate for some of the high-speed baud rates
such as 460800bps, for which the closest rate possible can be obtained
by dividing the baud base by 8, yielding the baud rate of 488281.25bps,
which is off by 5.9638%.  This is enough for data communication to break
with the remote end talking actual 460800bps, where missed stop bits
have been observed.

We can do better however, by taking advantage of a reduced oversampling
rate, which can be set to any integer value from 4 to 16 inclusive by
programming the TCR register, and by using the clock prescaler, which
can be set to any value from 1 to 63.875 in increments of 0.125 in the
CPR/CPR2 register pair.  The prescaler has to be explicitly enabled
though by setting bit 7 in the MCR or otherwise it is bypassed (in the
enhanced mode that we enable) as if the value of 1 was used.

Make use of these features then as follows:

- Set the baud base to 15625000, reflecting the minimum oversampling
  rate of 4 with the clock prescaler and divisor both set to 1.

- Override the `set_mctrl' and set the MCR shadow there so as to have
  MCR[7] always set and have the 8250 core propagate these settings.

- Override the `get_divisor' handler and determine a good combination of
  parameters by using a lookup table with predetermined value pairs of
  the oversampling rate and the clock prescaler and finding a pair that
  divides the input clock such that the quotient, when rounded to the
  nearest integer, deviates the least from the exact result.  Calculate
  the clock divisor accordingly.

  Scale the resulting oversampling rate (only by powers of two) if
  possible so as to maximise it, reducing the divisor accordingly, and
  avoid a divisor overflow for very low baud rates by scaling the
  oversampling rate and/or the prescaler even if that causes some
  accuracy loss.

  Also handle the historic spd_cust feature so as to allow one to set
  all the three parameters manually to arbitrary values, by keeping the
  low 16 bits for the divisor and then putting TCR in bits 19:16 and
  CPR/CPR2 in bits 28:20, sanitising the bit pattern supplied such as
  to clamp CPR/CPR2 values between 0.000 and 0.875 inclusive to 33.875.
  This preserves compatibility with any existing setups, that is where
  requesting a custom divisor that only has any bits set among the low
  16 the oversampling rate of 16 and the clock prescaler of 33.875 will
  be used as with the original 8250.

  Finally abuse the `frac' argument to store the determined bit patterns
  for the TCR, CPR and CPR2 registers.

- Override the `set_divisor' handler so as to set the TCR, CPR and CPR2
  registers from the `frac' value supplied.  Set the divisor as usual.

With the baud base set to 15625000 and the unsigned 16-bit UART_DIV_MAX
limitation imposed by `serial8250_get_baud_rate' standard baud rates
below 300bps become unavailable in the regular way, e.g. the rate of
200bps requires the baud base to be divided by 78125 and that is beyond
the unsigned 16-bit range.  The historic spd_cust feature can still be
used to obtain such rates if so required.

See Documentation/tty/device_drivers/oxsemi-tornado.rst for more details.

Signed-off-by: Maciej W. Rozycki 
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2204181519450.9383@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: 8250: Fold EndRun device support into OxSemi Tornado code

2022-08-17T12:42:22+00:00

[ Upstream commit 1f32c65bad24b9787d3e52843de375430e3df822 ]

The EndRun PTP/1588 dual serial port device is based on the Oxford
Semiconductor OXPCIe952 UART device with the PCI vendor:device ID set
for EndRun Technologies and uses the same sequence to determine the
number of ports available.  Despite that we have duplicate code
specific to the EndRun device.

Remove redundant code then and factor out OxSemi Tornado device
detection.

Signed-off-by: Maciej W. Rozycki 
Reviewed-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2204181516220.9383@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

tty: serial: fsl_lpuart: correct the count of break characters

2022-08-17T12:42:12+00:00

[ Upstream commit 707f816f25590c20e056b3bd4a17ce69b03fe856 ]

The LPUART can't distinguish between a break signal and a framing error,
so need to count the break characters if there is a framing error and
received data is zero instead of the parity error.

Fixes: 5541a9bacfe5 ("serial: fsl_lpuart: handle break and make sysrq work")
Reviewed-by: Michael Walle 
Signed-off-by: Sherry Sun 
Link: https://lore.kernel.org/r/20220725050115.12396-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: 8250_bcm2835aux: Add missing clk_disable_unprepare()

2022-08-17T12:42:12+00:00

[ Upstream commit b9f1736e475dba0d6da48fdcb831248ab1597886 ]

The error path when get clock frequency fails in bcm2835aux_serial
driver does not correctly disable the clock.

This flaw was found using a static analysis tool "Hulk Robot", which
reported the following warning when analyzing linux-next/master:

    drivers/tty/serial/8250/8250_bcm2835aux.c:
    warning: clk_disable_unprepare_missing.cocci

The cocci script checks for the existence of clk_disable_unprepare()
paired with clk_prepare_enable().

Add the missing clk_disable_unprepare() to the error path.

Fixes: fcc446c8aa63 ("serial: 8250_bcm2835aux: Add ACPI support")
Reported-by: Hulk Robot 
Reviewed-by: Florian Fainelli 
Signed-off-by: Guo Mengqi 
Link: https://lore.kernel.org/r/20220715023312.37808-1-guomengqi3@huawei.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: 8250_bcm7271: Save/restore RTS in suspend/resume

2022-08-17T12:42:06+00:00

[ Upstream commit 3182efd036c1b955403d131258234896cbd9fbeb ]

Commit 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming
from S2") prevented an early enabling of RTS during resume, but it did
not actively restore the RTS state after resume.

Fixes: 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming from S2")
Signed-off-by: Doug Berger 
Signed-off-by: Florian Fainelli 
Link: https://lore.kernel.org/r/20220714031316.404918-1-f.fainelli@gmail.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: 8250_fsl: Don't report FE, PE and OE twice

2022-08-17T12:42:04+00:00

[ Upstream commit 9d3aaceb73acadf134596a2f8db9c451c1332d3d ]

Some Freescale 8250 implementations have the problem that a single long
break results in one irq per character frame time. The code in
fsl8250_handle_irq() that is supposed to handle that uses the BI bit in
lsr_saved_flags to detect such a situation and then skip the second
received character. However it also stores other error bits and so after
a single frame error the character received in the next irq handling is
passed to the upper layer with a frame error, too.

So after a spike on the data line (which is correctly recognized as a
frame error) the following valid character is thrown away, because the
driver reports a frame error for that one, too.

To weaken this problem restrict saving LSR to only the BI bit.

Note however that the handling is still broken:

 - lsr_saved_flags is updated using orig_lsr which is the LSR content
   for the first received char, but there might be more in the FIFO, so
   a character is thrown away that is received later and not necessarily
   the one following the break.
 - The doubled break might be the 2nd and 3rd char in the FIFO, so the
   workaround doesn't catch these, because serial8250_rx_chars() doesn't
   handle the workaround.
 - lsr_saved_flags might have set UART_LSR_BI at the entry of
   fsl8250_handle_irq() which doesn't originate from
   fsl8250_handle_irq()'s "up->lsr_saved_flags |= orig_lsr &
   UART_LSR_BI;" but from e.g. from serial8250_tx_empty().
 - For a long or a short break this isn't about two characters, but more
   or only a single one.

Fixes: 9deaa53ac7fa ("serial: add irq handler for Freescale 16550 errata.")
Acked-by: Ilpo Järvinen 
Signed-off-by: Uwe Kleine-König 
Link: https://lore.kernel.org/r/20220704085119.55900-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: 8250: Export ICR access helpers for internal use

2022-08-17T12:41:59+00:00

[ Upstream commit cb5a40e3143bc64437858b337273fd63cc42e9c2 ]

Make ICR access helpers available outside 8250_port.c, however retain
them as ordinary static functions so as not to regress code generation.

This is because `serial_icr_write' is currently automatically inlined by
GCC, however `serial_icr_read' is not.  Making them both static inline
would grow code produced, e.g.:

$ i386-linux-gnu-size --format=gnu 8250_port-{old,new}.o
      text       data        bss      total filename
     15065       3378          0      18443 8250_port-old.o
     15289       3378          0      18667 8250_port-new.o

and:

$ riscv64-linux-gnu-size --format=gnu 8250_port-{old,new}.o
      text       data        bss      total filename
     16980       5306          0      22286 8250_port-old.o
     17124       5306          0      22430 8250_port-new.o

while making them external would needlessly add a new module interface
and lose the benefit from `serial_icr_write' getting inlined outside
8250_port.o.

Signed-off-by: Maciej W. Rozycki 
Reviewed-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2204181517500.9383@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: pic32: fix missing clk_disable_unprepare() on error in pic32_uart_startup()

2022-08-17T12:41:59+00:00

[ Upstream commit 6f3cdf2bf1ba9b70de6c2921a415951a0d59873b ]

Fix the missing clk_disable_unprepare() before return
from pic32_uart_startup() in the error handling case.

Fixes: 157b9394709e ("serial: pic32_uart: Add PIC32 UART driver")
Reported-by: Hulk Robot 
Reviewed-by: Jiri Slaby 
Signed-off-by: Yang Yingliang 
Link: https://lore.kernel.org/r/20220525021204.2407631-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

serial: pic32: free up irq names correctly

2022-08-17T12:41:59+00:00

[ Upstream commit fe36fa18ca77ca3ca9f90aab6cf39031416e432b ]

struct pic32_sport contains built-up names for irqs. These are freed
only in error path of pic32_uart_startup(). And even there, the freeing
happens before free_irq().

So fix this by:
* moving frees after free_irq(), and
* add frees to pic32_uart_shutdown() -- the opposite of
  pic32_uart_startup().

Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20220503063122.20957-11-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin