pinctrl: aspeed: Split out pinmux from general pinctrl

ASPEED have completely rearranged the System Control Unit register
layout with the AST2600. The existing code took advantage of the fact
that the AST2400 and AST2500 had layouts that were similar enough to
have little impact on the pinmux infrastructure (though there is a wart
with read-modify-write vs write-1-clear semantics of the hardware
strapping registers between the two).

Given that any similarity has been thrown out with the AST2600, separate
out the function applying an expression state to be driver-specific.
With it, extract out the pinmux macro jungle to its own header and
implementation so the pieces can be composed without dependency cycles.

Cc: Johnny Huang <johnny_huang@aspeedtech.com>
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://lore.kernel.org/r/20190628023838.15426-8-andrew@aj.id.au
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 96 insertions, 0 deletions

diff --git a/drivers/pinctrl/aspeed/pinmux-aspeed.c b/drivers/pinctrl/aspeed/pinmux-aspeed.c
new file mode 100644
index 000000000000..5b0fe178ccf2
--- /dev/null
+++ b/drivers/pinctrl/aspeed/pinmux-aspeed.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright (C) 2019 IBM Corp. */
+
+/* Pieces to enable drivers to implement the .set callback */
+
+#include "pinmux-aspeed.h"
+
+const char *const aspeed_pinmux_ips[] = {
+	[ASPEED_IP_SCU] = "SCU",
+	[ASPEED_IP_GFX] = "GFX",
+	[ASPEED_IP_LPC] = "LPC",
+};
+
+static inline void aspeed_sig_desc_print_val(
+		const struct aspeed_sig_desc *desc, bool enable, u32 rv)
+{
+	pr_debug("Want %s%X[0x%08X]=0x%X, got 0x%X from 0x%08X\n",
+			aspeed_pinmux_ips[desc->ip], desc->reg,
+			desc->mask, enable ? desc->enable : desc->disable,
+			(rv & desc->mask) >> __ffs(desc->mask), rv);
+}
+
+/**
+ * Query the enabled or disabled state of a signal descriptor
+ *
+ * @desc: The signal descriptor of interest
+ * @enabled: True to query the enabled state, false to query disabled state
+ * @map: The IP block's regmap instance
+ *
+ * Return: 1 if the descriptor's bitfield is configured to the state
+ * selected by @enabled, 0 if not, and less than zero if an unrecoverable
+ * failure occurred
+ *
+ * Evaluation of descriptor state is non-trivial in that it is not a binary
+ * outcome: The bitfields can be greater than one bit in size and thus can take
+ * a value that is neither the enabled nor disabled state recorded in the
+ * descriptor (typically this means a different function to the one of interest
+ * is enabled). Thus we must explicitly test for either condition as required.
+ */
+int aspeed_sig_desc_eval(const struct aspeed_sig_desc *desc,
+			 bool enabled, struct regmap *map)
+{
+	int ret;
+	unsigned int raw;
+	u32 want;
+
+	if (!map)
+		return -ENODEV;
+
+	ret = regmap_read(map, desc->reg, &raw);
+	if (ret)
+		return ret;
+
+	aspeed_sig_desc_print_val(desc, enabled, raw);
+	want = enabled ? desc->enable : desc->disable;
+
+	return ((raw & desc->mask) >> __ffs(desc->mask)) == want;
+}
+
+/**
+ * Query the enabled or disabled state for a mux function's signal on a pin
+ *
+ * @ctx: The driver context for the pinctrl IP
+ * @expr: An expression controlling the signal for a mux function on a pin
+ * @enabled: True to query the enabled state, false to query disabled state
+ *
+ * Return: 1 if the expression composed by @enabled evaluates true, 0 if not,
+ * and less than zero if an unrecoverable failure occurred.
+ *
+ * A mux function is enabled or disabled if the function's signal expression
+ * for each pin in the function's pin group evaluates true for the desired
+ * state. An signal expression evaluates true if all of its associated signal
+ * descriptors evaluate true for the desired state.
+ *
+ * If an expression's state is described by more than one bit, either through
+ * multi-bit bitfields in a single signal descriptor or through multiple signal
+ * descriptors of a single bit then it is possible for the expression to be in
+ * 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,
+			 const struct aspeed_sig_expr *expr, bool enabled)
+{
+	int i;
+	int ret;
+
+	for (i = 0; i < expr->ndescs; i++) {
+		const struct aspeed_sig_desc *desc = &expr->descs[i];
+
+		ret = aspeed_sig_desc_eval(desc, enabled, ctx->maps[desc->ip]);
+		if (ret <= 0)
+			return ret;
+	}
+
+	return 1;
+}