[PATCH] mpc83xx_clk: always treat MPC83XX_CLK_PCI as invalid

[Rasmus Villemoes]

The current mpc83xx_clk driver is broken for any board for which
mpc83xx_has_pci() is true, i.e. anything not MPC8308:

When is_clk_valid() reports that MPC83XX_CLK_PCI is valid,
init_all_clks() proceeds to call init_single_clk(), but that doesn't
know about either MPC83XX_CLK_PCI or has any handling of the
TYPE_SCCR_ONOFF mode correctly returned by retrieve_mode(). Hence
init_single_clk() ends up returning -EINVAL, and the whole board hangs
in serial_init().

The quickest fix is to simply pretend that clock is invalid for
all, since nobody can have been relying on it. Adding proper support
seems to be a bit more involved than just handling TYPE_SCCR_ONOFF:

- The power-on-reset value of SCCR[PCICM] is 0, so
  mpc83xx_clk_enable() would probably need to be tought to enable the
  clock.

- The frequency of PCI_SYNC_OUT is either SYS_CLK_IN or SYS_CLK_IN/2
  depending on the CFG_CLKIN_DIV configuration input, but that can't
  be read from software, so to properly fill out
  ->speed[MPC83XX_CLK_PCI] I think one would need guidance from
  Kconfig or dtb.

Partially fixes: 07d538d281 clk: Add MPC83xx clock driver

Signed-off-by: Rasmus Villemoes <rasmus.villemoes at prevas.dk>
---
 drivers/clk/mpc83xx_clk.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/mpc83xx_clk.c b/drivers/clk/mpc83xx_clk.c
index 32d2db9eda..1b2b216596 100644
--- a/drivers/clk/mpc83xx_clk.c
+++ b/drivers/clk/mpc83xx_clk.c
@@ -65,7 +65,10 @@ static inline bool is_clk_valid(struct udevice *clk, int id)
 	case MPC83XX_CLK_DMAC:
 		return (type == SOC_MPC8308) || (type == SOC_MPC8309);
 	case MPC83XX_CLK_PCI:
-		return mpc83xx_has_pci(type);
+		/*
+		 * FIXME: implement proper support for this.
+		 */
+		return 0 && mpc83xx_has_pci(type);
 	case MPC83XX_CLK_CSB:
 		return true;
 	case MPC83XX_CLK_I2C2:
-- 
2.23.0