[PATCH v4 0/3] Mixel DPHY support for i.MX8

[Guido Günther]

This adds initial support for the Mixel IP based mipi dphy as found on i.MX8
processors.  It has support for the i.MX8MQ, support for other variants can be
added - once the platform specific parts are in - via the provided devdata.
The driver is somewhat based on what's found in NXPs BSP.

Public documentation on the DPHY's registers is currently thin in the i.MX8
reference manuals (even on the i.MX8QXP form 11/18) so most of the values were
taken from existing drivers. Newer NXP drivers have a bit more details so where
possible the timings are calculated and validated.

This is based on linux-next as of 2019-02-28 (which already has Maxime Ripard's
dphy configuration helpers).

I'll also send out an initial version of a NWL mipi dsi host controller
driver using this. A 4.18 based tree using this driver, nwl and dcss
(the later from NXPs BSP) can be found here:

    https://source.puri.sm/guido.gunther/linux-imx8/commits/imx8-4.18-wip-nwl-dsi-rework

Changes form v3
* Check correct variable after devm_ioremap_resource
* Add Robert Chiras as Co-authored-by since he's the author
  of the driver in NXPs BSP.

Changes from v2
* As per review comments from Fabio Estevam
  * KConfig: select REGMAP_MMIO
  * Drop phy_read
  * Don't make phy_write inline
  * Remove duplicate debugging output
  * Comment style and typo fixes
  * Add #defines's for PLL lock timing values
  * Return correct error value when PLL fails to lock
  * Check error when enabling clock
  * Use devm_ioremap_resource
* As per review comments from Robert Chiras
  * Deassert PD_DPHY after PLL lock (as per mixel ref manual)
  * Assert PD_{DPHY,PLL} before power on (as per mixel ref manual)manual
* Add exit phy_op to reset CN/CM/CO

Changes from v1
* As per review comments from Fabio Estevam
  * Kconfig: tristate mixel dphy support.
  * Drop unused 'ret' in mixel_dphy_ref_power_off.
  * Match values of DPHY_RXL{PRP,DRP} to those of
    https://source.codeaurora.org/external/imx/linux-imx/log/?h=imx_4.14.78_1.0.0_ga
    The previous values were based on 4.9.
  * Use resource size on devm_ioremap, we have that in dt already.
  * Use regmap so it's simple to dump the registers.
  * Use regmap_read_poll_timeout instead of open coded loop.
  * Add undocumented rxhs_settle register
* As per review comments from Sam Ravnborg
  * Move driver to d/phy/freescale/
  * Move SPDX-License-Identifier to top of file.
  * Drop '/* #define DEBUG 1 */'.
  * Use GPL-2.0+ since the vendor driver uses that as well.
  * Drop the mutex, register access is now protected by regmap.
  * Fix various style / indentation issues.
* Check for register read, write and ioremap errors
* Improve phy timing calculations
  * Use LP clock rate where sensible, check for errors
  * Use ad hoc forumulas for timings involving hs clock
* Switch from dphy_ops to devdata. Other i.MX8 variants
  differ in register layout too
* Add Mixel Inc to vendor-prefixes.txt

Guido Günther (3):
  dt-bindings: Add vendor prefix for Mixel Inc
  dt-bindings: phy: Add documentation for mixel dphy
  phy: Add driver for mixel dphy found on imx8

 .../bindings/phy/mixel,mipi-dsi-phy.txt       |  29 +
 .../devicetree/bindings/vendor-prefixes.txt   |   1 +
 drivers/phy/freescale/Kconfig                 |  10 +
 drivers/phy/freescale/Makefile                |   1 +
 .../phy/freescale/phy-fsl-imx8-mipi-dphy.c    | 499 ++++++++++++++++++
 5 files changed, 540 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/phy/mixel,mipi-dsi-phy.txt
 create mode 100644 drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c

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2.20.1