[PATCH v5 00/15] clk: at91: updates for power management and dvfs

[Claudiu Beznea]

Hi,

This series addresses the clock power management for SAMA7G5 and also
updates the master clock driver and sam9x60-pll driver to accommodate
the requests at [1] and avoid overclocking of CPU and MCK0 domains while
changing the frequency via DVFS.

The power management part is implemented by adding
save_context()/restore_context() on each clock driver (patch 1/15). Since
the PM part is necessary only for backup mode (supported on SAMA5D2 and
SAMA7G5) the pmc.c has been adapted to call the
save_context()/restore_context() only on switches to/from backup mode
(patch 2/15).

Patch 3/15 adds the securam clock on SAMA7G5. This is necessary for
backup mode of SAMA7G5.

Patch 4/15 adapt SAMA7G5 MCK1..4 driver to use the defines at
include/linux/clk/at91_pmc.h introduced in commit ec03f18cc222
("clk: at91: add register definition for sama7g5's master clock").

Patch 5/15 improves a bit readabiblity in some places of master clock
driver.

Patch 6/15 enable the suspend/resume for clocks also for SAMA7G5.

Patches 7-10/15 adds fixes in master clock driver and sam9x60-pll driver.

Patches 11-12/15 address DVFS by adding notifiers for master clock driver
and sam9x60-pll driver to avoid overclocking for CPU domain and MCK0
domain.

Patch 13/15 removes the master clock prescaler from Linux clock tree
as it has been discovered a hardware bug on it and it may not lock
on some scenario although its output clock is stable.

Patch 14/15 decreases the low limit of MCK0 as it can go even to 32KHz.

Patch 15/15 uses clk_core_get_rate_recalc() in clk_rate_get().

Thank you,
Claudiu Beznea

[1] https://lore.kernel.org/lkml/20210105104426.4tmgc2l3vyicwedd@vireshk-i7/
[2] https://lore.kernel.org/lkml/163047507296.42057.10597374695758699868@swboyd.mtv.corp.google.com/ 

Changes in v5:
- dropped patches 16/17, 17/17 from previous version
- in patch 02/15:
	- use read_relaxed() to get the value at address pointed by 
	  at91_pmc_backup_suspend
	- removed of_find_device_by_node() from pmc_register_ops() since its
	  returned value was not used in the function (of_device_is_available()
	  is enough to know before mapping securam). of_find_device_by_node()
	  was the one which needed the changes of postcore_initcall() with
	  subsys_initcall() (as described in commit description from v4) thus
	  kept the postcore_initcall(); also updated the commit description
	  to reflect this.

Changes in v4:
- removed opp dependencies along with get_cpu_device() in patch 11/17 as
  those functionalities are not available at the initialization time for
  clocks instantiated with CLK_OF_DECLARE

Changes in v3:
- minor fixes in patch 1/7 (e.g. use regmap_read() + checks + update +
  regmap_write() sequence instead of regmap_read() + checks +
  regmap_update_bits()
- patch 4/17 has been updated after commit ec03f18cc222
  ("clk: at91: add register definition for sama7g5's master clock")
- patch 6-10/17, 14-17/17 are newly introduced
- notifier for sam9x60 div pll was introduced (patch 11/17) and
  notifier logic for master clock div has been changed (patch 12/17)
  to use safe divider on PRE_RATE_CHANGE events and update clock to highest
  possible rate on POST_RATE_CHANGE events
- master clock prescaler has been removed from Linux clock tree for
  SAMA7G5

Changes in v2:
- addressed code review comments
- collected tags

Claudiu Beznea (15):
  clk: at91: re-factor clocks suspend/resume
  clk: at91: pmc: execute suspend/resume only for backup mode
  clk: at91: sama7g5: add securam's peripheral clock
  clk: at91: clk-master: add register definition for sama7g5's master
    clock
  clk: at91: clk-master: improve readability by using local variables
  clk: at91: pmc: add sama7g5 to the list of available pmcs
  clk: at91: sam9x60-pll: use DIV_ROUND_CLOSEST_ULL
  clk: at91: clk-master: check if div or pres is zero
  clk: at91: clk-master: mask mckr against layout->mask
  clk: at91: clk-master: fix prescaler logic
  clk: at91: clk-sam9x60-pll: add notifier for div part of PLL
  clk: at91: clk-master: add notifier for divider
  clk: at91: sama7g5: remove prescaler part of master clock
  clk: at91: sama7g5: set low limit for mck0 at 32KHz
  clk: use clk_core_get_rate_recalc() in clk_rate_get()

 drivers/clk/at91/at91rm9200.c       |   2 +-
 drivers/clk/at91/at91sam9260.c      |   2 +-
 drivers/clk/at91/at91sam9g45.c      |   2 +-
 drivers/clk/at91/at91sam9n12.c      |   2 +-
 drivers/clk/at91/at91sam9rl.c       |   2 +-
 drivers/clk/at91/at91sam9x5.c       |   2 +-
 drivers/clk/at91/clk-generated.c    |  46 ++-
 drivers/clk/at91/clk-main.c         |  66 ++++
 drivers/clk/at91/clk-master.c       | 463 ++++++++++++++++++++++------
 drivers/clk/at91/clk-peripheral.c   |  40 ++-
 drivers/clk/at91/clk-pll.c          |  39 +++
 drivers/clk/at91/clk-programmable.c |  29 +-
 drivers/clk/at91/clk-sam9x60-pll.c  | 174 +++++++++--
 drivers/clk/at91/clk-system.c       |  20 ++
 drivers/clk/at91/clk-usb.c          |  27 ++
 drivers/clk/at91/clk-utmi.c         |  39 +++
 drivers/clk/at91/dt-compat.c        |   2 +-
 drivers/clk/at91/pmc.c              | 173 +++--------
 drivers/clk/at91/pmc.h              |  29 +-
 drivers/clk/at91/sam9x60.c          |   6 +-
 drivers/clk/at91/sama5d2.c          |   2 +-
 drivers/clk/at91/sama5d3.c          |   2 +-
 drivers/clk/at91/sama5d4.c          |   2 +-
 drivers/clk/at91/sama7g5.c          |  29 +-
 drivers/clk/clk.c                   |   2 +-
 25 files changed, 890 insertions(+), 312 deletions(-)

-- 
2.25.1