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Message-Id: <1493380324-20638-2-git-send-email-p.zabel@pengutronix.de>
Date: Fri, 28 Apr 2017 13:52:04 +0200
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Peter Rosin <peda@...ntia.se>
Cc: Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Sakari Ailus <sakari.ailus@....fi>,
Steve Longerbeam <slongerbeam@...il.com>,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel@...gutronix.de, Philipp Zabel <p.zabel@...gutronix.de>
Subject: [RFC v3 2/2] mux: mmio-based syscon mux controller
This adds a driver for mmio-based syscon multiplexers controlled by
bitfields in a syscon register range.
Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
---
Changes since v2:
- Updated CONFIG description to multi-mux
- Use mux_control_get_index instead of open-coding it
- Read mux-reg-masks and idle-states values in a single loop using
individual read_u32_index calls instead of using read_u32_array
- Verify bitmask
---
drivers/mux/Kconfig | 13 +++++
drivers/mux/Makefile | 1 +
drivers/mux/mux-mmio.c | 140 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 154 insertions(+)
create mode 100644 drivers/mux/mux-mmio.c
diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
index 34b8284d6d29e..50e7c5d557a05 100644
--- a/drivers/mux/Kconfig
+++ b/drivers/mux/Kconfig
@@ -43,4 +43,17 @@ config MUX_GPIO
To compile the driver as a module, choose M here: the module will
be called mux-gpio.
+config MUX_MMIO
+ tristate "MMIO register bitfield-controlled Multiplexer"
+ depends on OF && MFD_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.
+
+ To compile the driver as a module, choose M here: the module will
+ be called mux-mmio.
+
endif
diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
index b00a7d37d2fbe..6bac5b0fea137 100644
--- a/drivers/mux/Makefile
+++ b/drivers/mux/Makefile
@@ -5,3 +5,4 @@
obj-$(CONFIG_MULTIPLEXER) += mux-core.o
obj-$(CONFIG_MUX_ADG792A) += mux-adg792a.o
obj-$(CONFIG_MUX_GPIO) += mux-gpio.o
+obj-$(CONFIG_MUX_MMIO) += mux-mmio.o
diff --git a/drivers/mux/mux-mmio.c b/drivers/mux/mux-mmio.c
new file mode 100644
index 0000000000000..d2477d62d6eed
--- /dev/null
+++ b/drivers/mux/mux-mmio.c
@@ -0,0 +1,140 @@
+/*
+ * MMIO register bitfield-controlled multiplexer driver
+ *
+ * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@...gutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/mux/driver.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+static int mux_mmio_set(struct mux_control *mux, int state)
+{
+ struct regmap_field **fields = mux_chip_priv(mux->chip);
+
+ 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 of_device_id mux_mmio_dt_ids[] = {
+ { .compatible = "mmio-mux", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
+
+static int mux_mmio_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct regmap_field **fields;
+ struct mux_chip *mux_chip;
+ struct regmap *regmap;
+ int num_fields;
+ int ret;
+ int i;
+
+ regmap = syscon_node_to_regmap(np->parent);
+ if (IS_ERR(regmap)) {
+ ret = PTR_ERR(regmap);
+ dev_err(dev, "failed to get regmap: %d\n", ret);
+ return ret;
+ }
+
+ ret = of_property_count_u32_elems(np, "mux-reg-masks");
+ if (ret == 0 || ret % 2)
+ ret = -EINVAL;
+ if (ret < 0) {
+ dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
+ ret);
+ return ret;
+ }
+ num_fields = ret / 2;
+
+ mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
+ sizeof(*fields));
+ if (IS_ERR(mux_chip))
+ return PTR_ERR(mux_chip);
+
+ fields = mux_chip_priv(mux_chip);
+
+ for (i = 0; i < num_fields; i++) {
+ struct mux_control *mux = &mux_chip->mux[i];
+ struct reg_field field;
+ s32 idle_state = MUX_IDLE_AS_IS;
+ u32 reg, mask;
+ int bits;
+
+ ret = of_property_read_u32_index(np, "mux-reg-masks",
+ 2 * i, ®);
+ if (!ret)
+ ret = of_property_read_u32_index(np, "mux-reg-masks",
+ 2 * i + 1, &mask);
+ if (ret < 0) {
+ dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
+ i, ret);
+ return ret;
+ }
+
+ field.reg = reg;
+ field.msb = fls(mask) - 1;
+ field.lsb = ffs(mask) - 1;
+
+ if (mask != GENMASK(field.msb, field.lsb)) {
+ dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
+ i, mask);
+ return -EINVAL;
+ }
+
+ fields[i] = devm_regmap_field_alloc(dev, regmap, field);
+ if (IS_ERR(fields[i])) {
+ ret = PTR_ERR(fields[i]);
+ dev_err(dev, "bitfield %d: failed allocate: %d\n",
+ i, ret);
+ return ret;
+ }
+
+ bits = 1 + field.msb - field.lsb;
+ mux->states = 1 << bits;
+
+ of_property_read_u32_index(np, "idle-states", i, &idle_state);
+ if (idle_state != MUX_IDLE_AS_IS) {
+ if (idle_state < 0 || idle_state >= mux->states) {
+ dev_err(dev, "bitfield: %d: out of range idle state %d\n",
+ i, idle_state);
+ return -EINVAL;
+ }
+
+ mux->idle_state = idle_state;
+ }
+ }
+
+ mux_chip->ops = &mux_mmio_ops;
+
+ return devm_mux_chip_register(dev, mux_chip);
+}
+
+static struct platform_driver mux_mmio_driver = {
+ .driver = {
+ .name = "mmio-mux",
+ .of_match_table = of_match_ptr(mux_mmio_dt_ids),
+ },
+ .probe = mux_mmio_probe,
+};
+module_platform_driver(mux_mmio_driver);
+
+MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
+MODULE_AUTHOR("Philipp Zabel <p.zabel@...gutronix.de>");
+MODULE_LICENSE("GPL v2");
--
2.11.0
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