[PATCH v2 0/3] clk: socfpga: register the SP timer clocks early

[Adrian Ng Ho Yin <adrian.ho.yin.ng@altera.com>]

The DW APB timers on Stratix10, Agilex (including eASIC N5X) and Agilex5
are probed through TIMER_OF_DECLARE() from time_init(), but their clock,
l4_sp_clk, comes from a clock manager that is a platform driver
registered at core_initcall(). The timer's clk_get() returns
-EPROBE_DEFER, which timer_probe() does not report, and the timer is
never registered because TIMER_OF_DECLARE() callbacks are not retried.

Rather than moving the whole clock manager to CLK_OF_DECLARE() as v1 did,
this version keeps the platform driver and, following
clk-mt8173-infracfg.c, uses CLK_OF_DECLARE_DRIVER() to register only
l4_sp_clk and the clocks its rate depends on from of_clk_init():

  Agilex/N5X: boot_clk, main_pll, periph_pll, main_pll_c1, peri_pll_c1,
              noc_free_clk, l4_sp_clk
  Agilex5:    boot_clk, main_pll, periph_pll, main_pll_c3, peri_pll_c1,
              noc_free_clk, l4_sp_clk
  Stratix10:  boot_clk, main_pll, periph_pll, main_noc_base_clk,
              peri_noc_base_clk, noc_free_clk, l4_sp_clk

All other clock IDs return -EPROBE_DEFER until the platform driver probes,
registers the remaining clocks into the same provider and turns any
unused IDs into -ENOENT. If the early registration fails, probe falls
back to registering everything as before.

Boot-tested on Agilex7 (FM61), Stratix10 L-tile and Agilex5 (065B Premium
devkit), comparing each board with and without this series:

  - with the series, timer1 is registered as a clocksource within 0.5 ms
    of boot and timer0 as the broadcast clockevent device; without it,
    neither is registered and bc_hrtimer is used for broadcast instead
  - the clock manager still binds as a platform device, no devices are
    left deferred, and clocks registered at probe (EMAC, SD/MMC, USB,
    DMA, watchdog) have their expected rates and consumers

eASIC N5X is compile-tested only.

Changes in v2:
- Keep the clock managers as platform drivers instead of converting
  them to CLK_OF_DECLARE() (Brian)
- Register only l4_sp_clk and its parents early, using
  CLK_OF_DECLARE_DRIVER() as in clk-mt8173-infracfg.c, instead of the
  whole controller (Jerome)
- Return the result of of_clk_add_hw_provider() from probe
- Update subjects and commit messages to match the new approach

v1: https://lore.kernel.org/all/cover.1789096458.git.adrian.ho.yin.ng@altera.com/

Adrian Ng Ho Yin (3):
  clk: socfpga: agilex: register the SP timer clocks early
  clk: socfpga: agilex5: register the SP timer clocks early
  clk: socfpga: stratix10: register the SP timer clocks early

 drivers/clk/socfpga/clk-agilex.c  | 222 +++++++++++++++++++++++-------
 drivers/clk/socfpga/clk-agilex5.c | 138 +++++++++++++++----
 drivers/clk/socfpga/clk-s10.c     | 133 ++++++++++++++----
 3 files changed, 385 insertions(+), 108 deletions(-)


base-commit: 1e7f56205813a2c48cdb3e9a4b0a24f49fd9a548
-- 
2.49.GIT