[PATCH 2/3] TTY: add slave driver to power-on device via a regulator.

[NeilBrown <neilb@suse.de>]

The regulator is identified in devicetree as 'vdd-supply'

Signed-off-by: NeilBrown <neilb@suse.de>
---
 .../devicetree/bindings/serial/slave-reg.txt       |   18 ++++
 drivers/tty/Kconfig                                |    2 
 drivers/tty/Makefile                               |    1 
 drivers/tty/slaves/Kconfig                         |   12 ++
 drivers/tty/slaves/Makefile                        |    2 
 drivers/tty/slaves/tty-reg.c                       |  102 ++++++++++++++++++++
 6 files changed, 137 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/slave-reg.txt
 create mode 100644 drivers/tty/slaves/Kconfig
 create mode 100644 drivers/tty/slaves/Makefile
 create mode 100644 drivers/tty/slaves/tty-reg.c

diff --git a/Documentation/devicetree/bindings/serial/slave-reg.txt b/Documentation/devicetree/bindings/serial/slave-reg.txt
new file mode 100644
index 000000000000..7896bce8dfe4
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/slave-reg.txt
@@ -0,0 +1,18 @@
+Regulator powered UART-attached device
+
+Required properties:
+- compatible: "tty,regulator"
+- vdd-supply: regulator to power the device
+
+
+This is listed as a child node of a UART.  When the
+UART is opened, the device is powered.
+
+Example:
+
+&uart1 {
+	bluetooth {
+		compatible = "tty,regulator";
+		vdd-supply = <&vaux4>;
+	};
+};
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index b24aa010f68c..ea3383c71701 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -419,4 +419,6 @@ config DA_CONSOLE
 	help
 	  This enables a console on a Dash channel.
 
+source drivers/tty/slaves/Kconfig
+
 endif # TTY
diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
index 58ad1c05b7f8..45957d671e33 100644
--- a/drivers/tty/Makefile
+++ b/drivers/tty/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_R3964)		+= n_r3964.o
 obj-y				+= vt/
 obj-$(CONFIG_HVC_DRIVER)	+= hvc/
 obj-y				+= serial/
+obj-$(CONFIG_TTY_SLAVE)		+= slaves/
 
 # tty drivers
 obj-$(CONFIG_AMIGA_BUILTIN_SERIAL) += amiserial.o
diff --git a/drivers/tty/slaves/Kconfig b/drivers/tty/slaves/Kconfig
new file mode 100644
index 000000000000..2dd1acf80f8c
--- /dev/null
+++ b/drivers/tty/slaves/Kconfig
@@ -0,0 +1,12 @@
+menuconfig TTY_SLAVE
+	bool "TTY slave devices"
+	help
+	 Devices which attach via a uart, but need extra
+	 driver support for power management etc.
+
+if TTY_SLAVE
+
+config TTY_SLAVE_REGULATOR
+	tristate "TTY slave device powered by regulator"
+
+endif
diff --git a/drivers/tty/slaves/Makefile b/drivers/tty/slaves/Makefile
new file mode 100644
index 000000000000..e636bf49f1cc
--- /dev/null
+++ b/drivers/tty/slaves/Makefile
@@ -0,0 +1,2 @@
+
+obj-$(CONFIG_TTY_SLAVE_REGULATOR) += tty-reg.o
diff --git a/drivers/tty/slaves/tty-reg.c b/drivers/tty/slaves/tty-reg.c
new file mode 100644
index 000000000000..613f8b10967c
--- /dev/null
+++ b/drivers/tty/slaves/tty-reg.c
@@ -0,0 +1,102 @@
+/*
+ * tty-reg:
+ *   Support for any device which needs a regulator turned on
+ *   when a tty is opened.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/regulator/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/tty.h>
+
+struct tty_reg_data {
+	struct regulator *reg;
+	bool	reg_enabled;
+};
+
+static int tty_reg_runtime_resume(struct device *slave)
+{
+	struct tty_reg_data *data = dev_get_drvdata(slave);
+	if (!data->reg_enabled &&
+	    regulator_enable(data->reg) == 0) {
+		dev_dbg(slave, "power on\n");
+		data->reg_enabled = true;
+	}
+	return 0;
+}
+
+static int tty_reg_runtime_suspend(struct device *slave)
+{
+	struct tty_reg_data *data = dev_get_drvdata(slave);
+
+	if (data->reg_enabled &&
+	    regulator_disable(data->reg) == 0) {
+		dev_dbg(slave, "power off\n");
+		data->reg_enabled = false;
+	}
+	return 0;
+}
+
+static int tty_reg_probe(struct platform_device *pdev)
+{
+	struct tty_reg_data *data;
+	struct regulator *reg;
+	int err;
+
+	err = -ENODEV;
+	if (pdev->dev.parent == NULL)
+		goto out;
+	reg = devm_regulator_get(&pdev->dev, "vdd");
+	err = PTR_ERR(reg);
+	if (IS_ERR(reg))
+		goto out;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	err = -ENOMEM;
+	if (!data)
+		goto out;
+	data->reg = reg;
+	data->reg_enabled = false;
+	pm_runtime_enable(&pdev->dev);
+	platform_set_drvdata(pdev, data);
+	err = 0;
+out:
+	return err;
+}
+
+static struct of_device_id tty_reg_dt_ids[] = {
+	{ .compatible = "tty,regulator", },
+	{}
+};
+
+static const struct dev_pm_ops tty_reg_pm_ops = {
+	SET_RUNTIME_PM_OPS(tty_reg_runtime_suspend,
+			   tty_reg_runtime_resume, NULL)
+};
+
+static struct platform_driver tty_reg_driver = {
+	.driver.name	= "tty-regulator",
+	.driver.owner	= THIS_MODULE,
+	.driver.of_match_table = tty_reg_dt_ids,
+	.driver.pm	= &tty_reg_pm_ops,
+	.probe		= tty_reg_probe,
+};
+
+static int __init tty_reg_init(void)
+{
+	return platform_driver_register(&tty_reg_driver);
+}
+module_init(tty_reg_init);
+
+static void __exit tty_reg_exit(void)
+{
+	platform_driver_unregister(&tty_reg_driver);
+}
+module_exit(tty_reg_exit);
+
+MODULE_AUTHOR("NeilBrown <neilb@suse.de>");
+MODULE_DESCRIPTION("Serial port device which requires a regulator when open.");
+MODULE_LICENSE("GPL v2");