pinctrl: aspeed: Fix spurious mux failures on the AST2500

Commit 674fa8daa8c9 ("pinctrl: aspeed-g5: Delay acquisition of regmaps")
was determined to be a partial fix to the problem of acquiring the LPC
Host Controller and GFX regmaps: The AST2500 pin controller may need to
fetch syscon regmaps during expression evaluation as well as when
setting mux state. For example, this case is hit by attempting to export
pins exposing the LPC Host Controller as GPIOs.

An optional eval() hook is added to the Aspeed pinmux operation struct
and called from aspeed_sig_expr_eval() if the pointer is set by the
SoC-specific driver. This enables the AST2500 to perform the custom
action of acquiring its regmap dependencies as required.

John Wang tested the fix on an Inspur FP5280G2 machine (AST2500-based)
where the issue was found, and I've booted the fix on Witherspoon
(AST2500) and Palmetto (AST2400) machines, and poked at relevant pins
under QEMU by forcing mux configurations via devmem before exporting
GPIOs to exercise the driver.

Fixes: 7d29ed88acbb ("pinctrl: aspeed: Read and write bits in LPC and GFX controllers")
Fixes: 674fa8daa8c9 ("pinctrl: aspeed-g5: Delay acquisition of regmaps")
Reported-by: John Wang <wangzqbj@inspur.com>
Tested-by: John Wang <wangzqbj@inspur.com>
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>

Link: https://lore.kernel.org/r/20190829071738.2523-1-andrew@aj.id.au
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/pinctrl/aspeed/pinmux-aspeed.c b/drivers/pinctrl/aspeed/pinmux-aspeed.c
index 839c01b7953f..57305ca838a7 100644
--- a/drivers/pinctrl/aspeed/pinmux-aspeed.c
+++ b/drivers/pinctrl/aspeed/pinmux-aspeed.c
@@ -78,11 +78,14 @@ int aspeed_sig_desc_eval(const struct aspeed_sig_desc *desc,
  * neither the enabled nor disabled state. Thus we must explicitly test for
  * either condition as required.
  */
-int aspeed_sig_expr_eval(const struct aspeed_pinmux_data *ctx,
+int aspeed_sig_expr_eval(struct aspeed_pinmux_data *ctx,
 			 const struct aspeed_sig_expr *expr, bool enabled)
 {
-	int i;
 	int ret;
+	int i;
+
+	if (ctx->ops->eval)
+		return ctx->ops->eval(ctx, expr, enabled);
 
 	for (i = 0; i < expr->ndescs; i++) {
 		const struct aspeed_sig_desc *desc = &expr->descs[i];