drivers: mux: mmio-based syscon mux controller

This adds a driver for mmio-based syscon multiplexers controlled by
bitfields in a syscon register range.
This is heavily based on the linux mmio-mux driver.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>

drivers/mux/Kconfig

@@ -8,4 +8,18 @@ config MULTIPLEXER
 	 controllers. It provides the same API as Linux and mux drivers should
 	 be portable with a minimum effort.
 
+if MULTIPLEXER
+
+config MUX_MMIO
+	bool "MMIO register bitfield-controlled Multiplexer"
+	depends on MULTIPLEXER && SYSCON
+	help
+	  MMIO register bitfield-controlled Multiplexer controller.
+
+	  The driver builds multiplexer controllers for bitfields in a syscon
+	  register. For N bit wide bitfields, there will be 2^N possible
+	  multiplexer states.
+
+endif
+
 endmenu

drivers/mux/Makefile

@@ -4,3 +4,4 @@
 # Jean-Jacques Hiblot <jjhiblot@ti.com>
 
 obj-$(CONFIG_$(SPL_)MULTIPLEXER) += mux-uclass.o
+obj-$(CONFIG_$(SPL_)MUX_MMIO) += mmio.o

drivers/mux/mmio.c

@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MMIO register bitfield-controlled multiplexer driver
+ * Based on the linux mmio multiplexer driver
+ *
+ * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
+ * Copyright (C) 2019 Texas Instrument, Jean-jacques Hiblot <jjhiblot@ti.com>
+ */
+#include <common.h>
+#include <dm.h>
+#include <mux-internal.h>
+#include <regmap.h>
+#include <syscon.h>
+#include <dm/device.h>
+#include <dm/device_compat.h>
+#include <dm/read.h>
+#include <dm/devres.h>
+#include <dt-bindings/mux/mux.h>
+#include <linux/bitops.h>
+
+static int mux_mmio_set(struct mux_control *mux, int state)
+{
+	struct regmap_field **fields = dev_get_priv(mux->dev);
+
+	return regmap_field_write(fields[mux_control_get_index(mux)], state);
+}
+
+static const struct mux_control_ops mux_mmio_ops = {
+	.set = mux_mmio_set,
+};
+
+static const struct udevice_id mmio_mux_of_match[] = {
+	{ .compatible = "mmio-mux" },
+	{ /* sentinel */ },
+};
+
+static int mmio_mux_probe(struct udevice *dev)
+{
+	struct regmap_field **fields;
+	struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
+	struct regmap *regmap;
+	u32 *mux_reg_masks;
+	u32 *idle_states;
+	int num_fields;
+	int ret;
+	int i;
+
+	regmap = syscon_node_to_regmap(dev_ofnode(dev->parent));
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		dev_err(dev, "failed to get regmap: %d\n", ret);
+		return ret;
+	}
+
+	num_fields = dev_read_size(dev, "mux-reg-masks");
+	if (num_fields < 0)
+		return log_msg_ret("mux-reg-masks missing", -EINVAL);
+
+	num_fields /= sizeof(u32);
+	if (num_fields == 0 || num_fields % 2)
+		ret = -EINVAL;
+	num_fields = num_fields / 2;
+
+	ret = mux_alloc_controllers(dev, num_fields);
+	if (ret < 0)
+		return log_msg_ret("mux_alloc_controllers", ret);
+
+	fields = devm_kmalloc(dev, num_fields * sizeof(*fields), __GFP_ZERO);
+	if (!fields)
+		return -ENOMEM;
+	dev->priv = fields;
+
+	mux_reg_masks = devm_kmalloc(dev, num_fields * 2 * sizeof(u32),
+				     __GFP_ZERO);
+	if (!mux_reg_masks)
+		return -ENOMEM;
+
+	ret = dev_read_u32_array(dev, "mux-reg-masks", mux_reg_masks,
+				 num_fields * 2);
+	if (ret < 0)
+		return log_msg_ret("mux-reg-masks read", ret);
+
+	idle_states = devm_kmalloc(dev, num_fields * sizeof(u32), __GFP_ZERO);
+	if (!idle_states)
+		return -ENOMEM;
+
+	ret = dev_read_u32_array(dev, "idle-states", idle_states, num_fields);
+	if (ret < 0) {
+		log_err("idle-states");
+		devm_kfree(dev, idle_states);
+		idle_states = NULL;
+	}
+
+	for (i = 0; i < num_fields; i++) {
+		struct mux_control *mux = &mux_chip->mux[i];
+		struct reg_field field;
+		u32 reg, mask;
+		int bits;
+
+		reg = mux_reg_masks[2 * i];
+		mask = mux_reg_masks[2 * i + 1];
+
+		field.reg = reg;
+		field.msb = fls(mask) - 1;
+		field.lsb = ffs(mask) - 1;
+
+		if (mask != GENMASK(field.msb, field.lsb))
+			return log_msg_ret("invalid mask", -EINVAL);
+
+		fields[i] = devm_regmap_field_alloc(dev, regmap, field);
+		if (IS_ERR(fields[i])) {
+			ret = PTR_ERR(fields[i]);
+			return log_msg_ret("regmap_field_alloc", ret);
+		}
+
+		bits = 1 + field.msb - field.lsb;
+		mux->states = 1 << bits;
+
+		if (!idle_states)
+			continue;
+
+		if (idle_states[i] != MUX_IDLE_AS_IS &&
+		    idle_states[i] >= mux->states)
+			return log_msg_ret("idle-states range", -EINVAL);
+
+		mux->idle_state = idle_states[i];
+	}
+
+	devm_kfree(dev, mux_reg_masks);
+	if (idle_states)
+		devm_kfree(dev, idle_states);
+
+	return 0;
+}
+
+U_BOOT_DRIVER(mmio_mux) = {
+	.name = "mmio-mux",
+	.id = UCLASS_MUX,
+	.of_match = mmio_mux_of_match,
+	.probe = mmio_mux_probe,
+	.ops = &mux_mmio_ops,
+};