[PATCH v2 1/4] input: Add new sun4i-lradc-keys driver

Hans de Goede
2014-10-21T08:24:47Z

Allwinnner sunxi SoCs have a low resolution adc (called lradc) which is
specifically designed to have various (tablet) keys (ie home, back, search,
etc). attached to it using a resistor network. This adds a driver for this.

There are 2 channels, currently this driver only supports chan0 since there
are no boards known to use chan1.

This has been tested on an olimex a10s-olinuxino-micro, a13-olinuxino, and
a20-olinuxino-micro.

Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
--
Changes in v2:
-Change devicetree bindings to use a per key subnode, like gpio-keys does
---
.../devicetree/bindings/input/sun4i-lradc-keys.txt | 57 +++++
MAINTAINERS | 7 +
drivers/input/keyboard/Kconfig | 10 +
drivers/input/keyboard/Makefile | 1 +
drivers/input/keyboard/sun4i-lradc-keys.c | 259 +++++++++++++++++++++
5 files changed, 334 insertions(+)
create mode 100644 Documentation/devicetree/bindings/input/sun4i-lradc-keys.txt
create mode 100644 drivers/input/keyboard/sun4i-lradc-keys.c

diff --git a/Documentation/devicetree/bindings/input/sun4i-lradc-keys.txt b/Documentation/devicetree/bindings/input/sun4i-lradc-keys.txt
new file mode 100644
index 0000000..36a141b
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/sun4i-lradc-keys.txt
@@ -0,0 +1,57 @@
+Allwinner sun4i low res adc attached tablet keys
+------------------------------------------------
+
+Required properties:
+ - compatible: "allwinner,sun4i-lradc-keys"
+ - reg: mmio address range of the chip
+ - interrupts: interrupt to which the chip is connected
+ - vref-supply: powersupply for the lradc reference voltage
+
+Each key is represented as a sub-node of "allwinner,sun4i-lradc-keys":
+
+Required subnode-properties:
+ - label: Descriptive name of the key.
+ - linux,code: Keycode to emit.
+ - channel: Channel this key is attached to, mut be 0 or 1.
+ - voltage: Voltage in µV at lradc input when this key is pressed.
+
+Example:
+
+#include <dt-bindings/input/input.h>
+
+ lradc: lradc@01c22800 {
+ compatible = "allwinner,sun4i-lradc-keys";
+ reg = <0x01c22800 0x100>;
+ interrupts = <31>;
+ vref-supply = <&reg_vcc3v0>;
+ button@19 {
+ label = "Volume Up";
+ linux,code = <KEY_VOLUMEUP>;
+ channel = <0>;
+ voltage = <191274>;
+ };
+ button@39 {
+ label = "Volume Down";
+ linux,code = <KEY_VOLUMEDOWN>;
+ channel = <0>;
+ voltage = <392644>;
+ };
+ button@60 {
+ label = "Menu";
+ linux,code = <KEY_MENU>;
+ channel = <0>;
+ voltage = <601151>;
+ };
+ button@80 {
+ label = "Enter";
+ linux,code = <KEY_ENTER>;
+ channel = <0>;
+ voltage = <795090>;
+ };
+ button@98 {
+ label = "Home";
+ linux,code = <KEY_HOME>;
+ channel = <0>;
+ voltage = <987387>;
+ };
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index a20df9b..73d1aef 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8932,6 +8932,13 @@ F: arch/m68k/sun3*/
F: arch/m68k/include/asm/sun3*
F: drivers/net/ethernet/i825xx/sun3*

+SUN4I LOW RES ADC ATTACHED TABLET KEYS DRIVER
+M: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
+L: linux-input-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
+S: Maintained
+F: Documentation/devicetree/bindings/input/sun4i-lradc-keys.txt
+F: drivers/input/keyboard/sun4i-lradc-keys.c
+
SUNDANCE NETWORK DRIVER
M: Denis Kirjanov <kda-u1c8ncikuMvVAZt0uhVF+Ni2O/JbrIOy@public.gmane.org>
L: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index a3958c6..2d11b44 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -567,6 +567,16 @@ config KEYBOARD_STMPE
To compile this driver as a module, choose M here: the module will be
called stmpe-keypad.

+config KEYBOARD_SUN4I_LRADC
+ tristate "Allwinner sun4i low res adc attached tablet keys support"
+ depends on ARCH_SUNXI
+ help
+ This selects support for the Allwinner low res adc attached tablet
+ keys found on Allwinner sunxi SoCs.
+
+ To compile this driver as a module, choose M here: the
+ module will be called sun4i-lradc-keys.
+
config KEYBOARD_DAVINCI
tristate "TI DaVinci Key Scan"
depends on ARCH_DAVINCI_DM365
diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
index 0a33456..a35269a 100644
--- a/drivers/input/keyboard/Makefile
+++ b/drivers/input/keyboard/Makefile
@@ -53,6 +53,7 @@ obj-$(CONFIG_KEYBOARD_SPEAR) += spear-keyboard.o
obj-$(CONFIG_KEYBOARD_STMPE) += stmpe-keypad.o
obj-$(CONFIG_KEYBOARD_STOWAWAY) += stowaway.o
obj-$(CONFIG_KEYBOARD_ST_KEYSCAN) += st-keyscan.o
+obj-$(CONFIG_KEYBOARD_SUN4I_LRADC) += sun4i-lradc-keys.o
obj-$(CONFIG_KEYBOARD_SUNKBD) += sunkbd.o
obj-$(CONFIG_KEYBOARD_TC3589X) += tc3589x-keypad.o
obj-$(CONFIG_KEYBOARD_TEGRA) += tegra-kbc.o
diff --git a/drivers/input/keyboard/sun4i-lradc-keys.c b/drivers/input/keyboard/sun4i-lradc-keys.c
new file mode 100644
index 0000000..63a1aff
--- /dev/null
+++ b/drivers/input/keyboard/sun4i-lradc-keys.c
@@ -0,0 +1,259 @@
+/*
+ * Allwinner sun4i low res adc attached tablet keys driver
+ *
+ * Copyright (C) 2014 Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+/*
+ * Allwinnner sunxi SoCs have a lradc which is specifically designed to have
+ * various (tablet) keys (ie home, back, search, etc). attached to it using
+ * a resistor network. This driver is for the keys on such boards.
+ *
+ * There are 2 channels, currently this driver only supports channel 0 since
+ * there are no boards known to use channel 1.
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#define LRADC_CTRL 0x00
+#define LRADC_INTC 0x04
+#define LRADC_INTS 0x08
+#define LRADC_DATA0 0x0c
+#define LRADC_DATA1 0x10
+
+/* LRADC_CTRL bits */
+#define FIRST_CONVERT_DLY(x) ((x) << 24) /* 8 bits */
+#define CHAN_SELECT(x) ((x) << 22) /* 2 bits */
+#define CONTINUE_TIME_SEL(x) ((x) << 16) /* 4 bits */
+#define KEY_MODE_SEL(x) ((x) << 12) /* 2 bits */
+#define LEVELA_B_CNT(x) ((x) << 8) /* 4 bits */
+#define HOLD_EN(x) ((x) << 6)
+#define LEVELB_VOL(x) ((x) << 4) /* 2 bits */
+#define SAMPLE_RATE(x) ((x) << 2) /* 2 bits */
+#define ENABLE(x) ((x) << 0)
+
+/* LRADC_INTC and LRADC_INTS bits */
+#define CHAN1_KEYUP_IRQ BIT(12)
+#define CHAN1_ALRDY_HOLD_IRQ BIT(11)
+#define CHAN1_HOLD_IRQ BIT(10)
+#define CHAN1_KEYDOWN_IRQ BIT(9)
+#define CHAN1_DATA_IRQ BIT(8)
+#define CHAN0_KEYUP_IRQ BIT(4)
+#define CHAN0_ALRDY_HOLD_IRQ BIT(3)
+#define CHAN0_HOLD_IRQ BIT(2)
+#define CHAN0_KEYDOWN_IRQ BIT(1)
+#define CHAN0_DATA_IRQ BIT(0)
+
+struct sun4i_lradc_keymap {
+ u32 voltage;
+ u32 keycode;
+};
+
+struct sun4i_lradc_data {
+ struct device *dev;
+ struct input_dev *input;
+ void __iomem *base;
+ struct regulator *vref_supply;
+ struct sun4i_lradc_keymap *chan0_map;
+ u32 chan0_map_count;
+ u32 chan0_keycode;
+ u32 vref;
+};
+
+static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
+{
+ struct sun4i_lradc_data *lradc = dev_id;
+ u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;
+
+ ints = readl(lradc->base + LRADC_INTS);
+
+ /*
+ * lradc supports only one keypress at a time, release does not give
+ * any info as to which key was released, so we cache the keycode.
+ */
+ if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
+ val = readl(lradc->base + LRADC_DATA0) & 0x3f;
+ voltage = val * lradc->vref / 63;
+
+ for (i = 0; i < lradc->chan0_map_count; i++) {
+ diff = abs(lradc->chan0_map[i].voltage - voltage);
+ if (diff < closest) {
+ closest = diff;
+ keycode = lradc->chan0_map[i].keycode;
+ }
+ }
+
+ lradc->chan0_keycode = keycode;
+ input_report_key(lradc->input, lradc->chan0_keycode, 1);
+ }
+
+ if (ints & CHAN0_KEYUP_IRQ) {
+ input_report_key(lradc->input, lradc->chan0_keycode, 0);
+ lradc->chan0_keycode = 0;
+ }
+
+ input_sync(lradc->input);
+
+ writel(ints, lradc->base + LRADC_INTS);
+
+ return IRQ_HANDLED;
+}
+
+static int sun4i_lradc_open(struct input_dev *dev)
+{
+ struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
+ int ret;
+
+ ret = regulator_enable(lradc->vref_supply);
+ if (ret)
+ return ret;
+
+ /* lradc Vref internally is divided by 2/3 */
+ lradc->vref = regulator_get_voltage(lradc->vref_supply) * 2 / 3;
+
+ /*
+ * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
+ * stabilize on press, wait (1 + 1) * 4 ms for key release
+ */
+ writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
+ SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL);
+
+ writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC);
+
+ return 0;
+}
+
+static void sun4i_lradc_close(struct input_dev *dev)
+{
+ struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
+
+ /* Disable lradc, leave other settings unchanged */
+ writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
+ SAMPLE_RATE(2), lradc->base + LRADC_CTRL);
+ writel(0, lradc->base + LRADC_INTC);
+
+ regulator_disable(lradc->vref_supply);
+}
+
+static int sun4i_lradc_probe(struct platform_device *pdev)
+{
+ struct sun4i_lradc_data *lradc;
+ struct device *dev = &pdev->dev;
+ struct device_node *pp, *np = dev->of_node;
+ u32 channel;
+ int i, ret;
+
+ lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
+ if (!lradc)
+ return -ENOMEM;
+
+ lradc->chan0_map_count = of_get_child_count(np);
+ lradc->chan0_map = devm_kmalloc(dev, lradc->chan0_map_count *
+ sizeof(struct sun4i_lradc_keymap), GFP_KERNEL);
+ if (!lradc->chan0_map)
+ return -ENOMEM;
+
+ i = 0;
+ for_each_child_of_node(np, pp) {
+ struct sun4i_lradc_keymap *map = &lradc->chan0_map[i];
+
+ ret = of_property_read_u32(pp, "channel", &channel);
+ if (ret || channel != 0) {
+ dev_err(dev, "%s: Inval channel prop\n", pp->name);
+ return -EINVAL;
+ }
+
+ ret = of_property_read_u32(pp, "voltage", &map->voltage);
+ if (ret) {
+ dev_err(dev, "%s: Inval voltage prop\n", pp->name);
+ return -EINVAL;
+ }
+
+ ret = of_property_read_u32(pp, "linux,code", &map->keycode);
+ if (ret) {
+ dev_err(dev, "%s: Inval linux,code prop\n", pp->name);
+ return -EINVAL;
+ }
+
+ i++;
+ }
+
+ lradc->vref_supply = devm_regulator_get(dev, "vref");
+ if (IS_ERR(lradc->vref_supply))
+ return PTR_ERR(lradc->vref_supply);
+
+ lradc->dev = dev;
+ lradc->input = devm_input_allocate_device(dev);
+ if (!lradc->input)
+ return -ENOMEM;
+
+ lradc->input->name = pdev->name;
+ lradc->input->phys = "sun4i_lradc/input0";
+ lradc->input->open = sun4i_lradc_open;
+ lradc->input->close = sun4i_lradc_close;
+ lradc->input->id.bustype = BUS_HOST;
+ lradc->input->id.vendor = 0x0001;
+ lradc->input->id.product = 0x0001;
+ lradc->input->id.version = 0x0100;
+ lradc->input->evbit[0] = BIT(EV_SYN) | BIT(EV_KEY);
+ for (i = 0; i < lradc->chan0_map_count; i++)
+ set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit);
+ input_set_drvdata(lradc->input, lradc);
+
+ lradc->base = devm_ioremap_resource(dev,
+ platform_get_resource(pdev, IORESOURCE_MEM, 0));
+ if (IS_ERR(lradc->base))
+ return PTR_ERR(lradc->base);
+
+ ret = devm_request_irq(dev, platform_get_irq(pdev, 0), sun4i_lradc_irq,
+ 0, "sun4i-lradc-keys", lradc);
+ if (ret)
+ return ret;
+
+ ret = input_register_device(lradc->input);
+ if (ret)
+ return ret;
+
+ platform_set_drvdata(pdev, lradc);
+ return 0;
+}
+
+static const struct of_device_id sun4i_lradc_of_match[] = {
+ { .compatible = "allwinner,sun4i-lradc-keys", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
+
+static struct platform_driver sun4i_lradc_driver = {
+ .driver = {
+ .owner = THIS_MODULE,
+ .name = "sun4i-lradc-keys",
+ .of_match_table = of_match_ptr(sun4i_lradc_of_match),
+ },
+ .probe = sun4i_lradc_probe,
+};
+
+module_platform_driver(sun4i_lradc_driver);
+
+MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
+MODULE_AUTHOR("Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>");
+MODULE_LICENSE("GPL");
--
2.1.0

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