[PATCH v9 03/10] mux: minimal mux subsystem and gpio-based mux controller

2017-02-08 Thread Peter Rosin 
Add a new minimalistic subsystem that handles multiplexer controllers.
When multiplexers are used in various places in the kernel, and the
same multiplexer controller can be used for several independent things,
there should be one place to implement support for said multiplexer
controller.

A single multiplexer controller can also be used to control several
parallel multiplexers, that are in turn used by different subsystems
in the kernel, leading to a need to coordinate multiplexer accesses.
The multiplexer subsystem handles this coordination.

This new mux controller subsystem initially comes with a single backend
driver that controls gpio based multiplexers. Even though not needed by
this initial driver, the mux controller subsystem is prepared to handle
chips with multiple (independent) mux controllers.

Reviewed-by: Jonathan Cameron 
Signed-off-by: Peter Rosin 
---
 Documentation/driver-model/devres.txt |   8 +
 MAINTAINERS   |   2 +
 drivers/Kconfig   |   2 +
 drivers/Makefile  |   1 +
 drivers/mux/Kconfig   |  33 +++
 drivers/mux/Makefile  |   6 +
 drivers/mux/mux-core.c| 414 ++
 drivers/mux/mux-gpio.c| 114 ++
 include/linux/mux.h   | 248 
 9 files changed, 828 insertions(+)
 create mode 100644 drivers/mux/Kconfig
 create mode 100644 drivers/mux/Makefile
 create mode 100644 drivers/mux/mux-core.c
 create mode 100644 drivers/mux/mux-gpio.c
 create mode 100644 include/linux/mux.h

diff --git a/Documentation/driver-model/devres.txt 
b/Documentation/driver-model/devres.txt
index dc51fb024190..1e9ae701a587 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -332,6 +332,14 @@ MEM
 MFD
   devm_mfd_add_devices()
 
+MUX
+  devm_mux_chip_alloc()
+  devm_mux_chip_free()
+  devm_mux_chip_register()
+  devm_mux_chip_unregister()
+  devm_mux_control_get()
+  devm_mux_control_put()
+
 PER-CPU MEM
   devm_alloc_percpu()
   devm_free_percpu()
diff --git a/MAINTAINERS b/MAINTAINERS
index 8a0adb1e6194..353fa1f37a40 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8500,6 +8500,8 @@ M:Peter Rosin 
 S: Maintained
 F: Documentation/devicetree/bindings/mux/
 F: include/linux/dt-bindings/mux/
+F: include/linux/mux.h
+F: drivers/mux/
 
 MULTISOUND SOUND DRIVER
 M: Andrew Veliath 
diff --git a/drivers/Kconfig b/drivers/Kconfig
index e1e2066cecdb..ea231018089e 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -202,4 +202,6 @@ source "drivers/hwtracing/intel_th/Kconfig"
 
 source "drivers/fpga/Kconfig"
 
+source "drivers/mux/Kconfig"
+
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index 060026a02f59..8ff0460bb2f8 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -173,3 +173,4 @@ obj-$(CONFIG_STM)   += hwtracing/stm/
 obj-$(CONFIG_ANDROID)  += android/
 obj-$(CONFIG_NVMEM)+= nvmem/
 obj-$(CONFIG_FPGA) += fpga/
+obj-$(CONFIG_MULTIPLEXER)  += mux/
diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
new file mode 100644
index ..57e6f4e5fda9
--- /dev/null
+++ b/drivers/mux/Kconfig
@@ -0,0 +1,33 @@
+#
+# Multiplexer devices
+#
+
+menuconfig MULTIPLEXER
+   bool "Multiplexer subsystem"
+   help
+ Multiplexer controller subsystem. Multiplexers are used in a
+ variety of settings, and this subsystem abstracts their use
+ so that the rest of the kernel sees a common interface. When
+ multiple parallel multiplexers are controlled by one single
+ multiplexer controller, this subsystem also coordinates the
+ multiplexer accesses.
+
+ If unsure, say no.
+
+if MULTIPLEXER
+
+config MUX_GPIO
+   tristate "GPIO-controlled Multiplexer"
+   depends on OF && GPIOLIB
+   help
+ GPIO-controlled Multiplexer controller.
+
+ The driver builds a single multiplexer controller using a number
+ of gpio pins. For N pins, there will be 2^N possible multiplexer
+ states. The GPIO pins can be connected (by the hardware) to several
+ multiplexers, which in that case will be operated in parallel.
+
+ To compile the driver as a module, choose M here: the module will
+ be called mux-gpio.
+
+endif
diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
new file mode 100644
index ..facc43da3648
--- /dev/null
+++ b/drivers/mux/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for multiplexer devices.
+#
+
+obj-$(CONFIG_MULTIPLEXER)  += mux-core.o
+obj-$(CONFIG_MUX_GPIO) += mux-gpio.o
diff --git a/drivers/mux/mux-core.c b/drivers/mux/mux-core.c
new file mode 100644
index ..46088a0f9677
--- /dev/null
+++ b/drivers/mux/mux-core.c
@@ -0,0 +1,414 @@
+/*
+ * Multiplexer subsystem
+ *

[PATCH v9 03/10] mux: minimal mux subsystem and gpio-based mux controller

2017-02-08 Thread Peter Rosin 
Add a new minimalistic subsystem that handles multiplexer controllers.
When multiplexers are used in various places in the kernel, and the
same multiplexer controller can be used for several independent things,
there should be one place to implement support for said multiplexer
controller.

A single multiplexer controller can also be used to control several
parallel multiplexers, that are in turn used by different subsystems
in the kernel, leading to a need to coordinate multiplexer accesses.
The multiplexer subsystem handles this coordination.

This new mux controller subsystem initially comes with a single backend
driver that controls gpio based multiplexers. Even though not needed by
this initial driver, the mux controller subsystem is prepared to handle
chips with multiple (independent) mux controllers.

Reviewed-by: Jonathan Cameron 
Signed-off-by: Peter Rosin 
---
 Documentation/driver-model/devres.txt |   8 +
 MAINTAINERS   |   2 +
 drivers/Kconfig   |   2 +
 drivers/Makefile  |   1 +
 drivers/mux/Kconfig   |  33 +++
 drivers/mux/Makefile  |   6 +
 drivers/mux/mux-core.c| 414 ++
 drivers/mux/mux-gpio.c| 114 ++
 include/linux/mux.h   | 248 
 9 files changed, 828 insertions(+)
 create mode 100644 drivers/mux/Kconfig
 create mode 100644 drivers/mux/Makefile
 create mode 100644 drivers/mux/mux-core.c
 create mode 100644 drivers/mux/mux-gpio.c
 create mode 100644 include/linux/mux.h

diff --git a/Documentation/driver-model/devres.txt 
b/Documentation/driver-model/devres.txt
index dc51fb024190..1e9ae701a587 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -332,6 +332,14 @@ MEM
 MFD
   devm_mfd_add_devices()
 
+MUX
+  devm_mux_chip_alloc()
+  devm_mux_chip_free()
+  devm_mux_chip_register()
+  devm_mux_chip_unregister()
+  devm_mux_control_get()
+  devm_mux_control_put()
+
 PER-CPU MEM
   devm_alloc_percpu()
   devm_free_percpu()
diff --git a/MAINTAINERS b/MAINTAINERS
index 8a0adb1e6194..353fa1f37a40 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8500,6 +8500,8 @@ M:Peter Rosin 
 S: Maintained
 F: Documentation/devicetree/bindings/mux/
 F: include/linux/dt-bindings/mux/
+F: include/linux/mux.h
+F: drivers/mux/
 
 MULTISOUND SOUND DRIVER
 M: Andrew Veliath 
diff --git a/drivers/Kconfig b/drivers/Kconfig
index e1e2066cecdb..ea231018089e 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -202,4 +202,6 @@ source "drivers/hwtracing/intel_th/Kconfig"
 
 source "drivers/fpga/Kconfig"
 
+source "drivers/mux/Kconfig"
+
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index 060026a02f59..8ff0460bb2f8 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -173,3 +173,4 @@ obj-$(CONFIG_STM)   += hwtracing/stm/
 obj-$(CONFIG_ANDROID)  += android/
 obj-$(CONFIG_NVMEM)+= nvmem/
 obj-$(CONFIG_FPGA) += fpga/
+obj-$(CONFIG_MULTIPLEXER)  += mux/
diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
new file mode 100644
index ..57e6f4e5fda9
--- /dev/null
+++ b/drivers/mux/Kconfig
@@ -0,0 +1,33 @@
+#
+# Multiplexer devices
+#
+
+menuconfig MULTIPLEXER
+   bool "Multiplexer subsystem"
+   help
+ Multiplexer controller subsystem. Multiplexers are used in a
+ variety of settings, and this subsystem abstracts their use
+ so that the rest of the kernel sees a common interface. When
+ multiple parallel multiplexers are controlled by one single
+ multiplexer controller, this subsystem also coordinates the
+ multiplexer accesses.
+
+ If unsure, say no.
+
+if MULTIPLEXER
+
+config MUX_GPIO
+   tristate "GPIO-controlled Multiplexer"
+   depends on OF && GPIOLIB
+   help
+ GPIO-controlled Multiplexer controller.
+
+ The driver builds a single multiplexer controller using a number
+ of gpio pins. For N pins, there will be 2^N possible multiplexer
+ states. The GPIO pins can be connected (by the hardware) to several
+ multiplexers, which in that case will be operated in parallel.
+
+ To compile the driver as a module, choose M here: the module will
+ be called mux-gpio.
+
+endif
diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
new file mode 100644
index ..facc43da3648
--- /dev/null
+++ b/drivers/mux/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for multiplexer devices.
+#
+
+obj-$(CONFIG_MULTIPLEXER)  += mux-core.o
+obj-$(CONFIG_MUX_GPIO) += mux-gpio.o
diff --git a/drivers/mux/mux-core.c b/drivers/mux/mux-core.c
new file mode 100644
index ..46088a0f9677
--- /dev/null
+++ b/drivers/mux/mux-core.c
@@ -0,0 +1,414 @@
+/*
+ * Multiplexer subsystem
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ *
+ * Author: Peter