--- /dev/null
+/*
+ * Allwinner sun4i low res adc attached tablet keys driver
+ *
+ * Copyright (C) 2014 Hans de Goede <hdegoede@redhat.com>
+ *
+ * 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_KEYUP_IRQ) {
+ input_report_key(lradc->input, lradc->chan0_keycode, 0);
+ lradc->chan0_keycode = 0;
+ }
+
+ 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);
+ }
+
+ 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 error;
+
+ error = regulator_enable(lradc->vref_supply);
+ if (error)
+ return error;
+
+ /* 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_load_dt_keymap(struct device *dev,
+ struct sun4i_lradc_data *lradc)
+{
+ struct device_node *np, *pp;
+ int i;
+ int error;
+
+ np = dev->of_node;
+ if (!np)
+ return -EINVAL;
+
+ lradc->chan0_map_count = of_get_child_count(np);
+ if (lradc->chan0_map_count == 0) {
+ dev_err(dev, "keymap is missing in device tree\n");
+ return -EINVAL;
+ }
+
+ lradc->chan0_map = devm_kmalloc_array(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];
+ u32 channel;
+
+ error = of_property_read_u32(pp, "channel", &channel);
+ if (error || channel != 0) {
+ dev_err(dev, "%s: Inval channel prop\n", pp->name);
+ return -EINVAL;
+ }
+
+ error = of_property_read_u32(pp, "voltage", &map->voltage);
+ if (error) {
+ dev_err(dev, "%s: Inval voltage prop\n", pp->name);
+ return -EINVAL;
+ }
+
+ error = of_property_read_u32(pp, "linux,code", &map->keycode);
+ if (error) {
+ dev_err(dev, "%s: Inval linux,code prop\n", pp->name);
+ return -EINVAL;
+ }
+
+ i++;
+ }
+
+ return 0;
+}
+
+static int sun4i_lradc_probe(struct platform_device *pdev)
+{
+ struct sun4i_lradc_data *lradc;
+ struct device *dev = &pdev->dev;
+ int i;
+ int error;
+
+ lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
+ if (!lradc)
+ return -ENOMEM;
+
+ error = sun4i_lradc_load_dt_keymap(dev, lradc);
+ if (error)
+ return error;
+
+ 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;
+
+ __set_bit(EV_KEY, lradc->input->evbit);
+ 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);
+
+ error = devm_request_irq(dev, platform_get_irq(pdev, 0),
+ sun4i_lradc_irq, 0,
+ "sun4i-a10-lradc-keys", lradc);
+ if (error)
+ return error;
+
+ error = input_register_device(lradc->input);
+ if (error)
+ return error;
+
+ platform_set_drvdata(pdev, lradc);
+ return 0;
+}
+
+static const struct of_device_id sun4i_lradc_of_match[] = {
+ { .compatible = "allwinner,sun4i-a10-lradc-keys", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
+
+static struct platform_driver sun4i_lradc_driver = {
+ .driver = {
+ .name = "sun4i-a10-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@redhat.com>");
+MODULE_LICENSE("GPL");
projects / GitHub / exynos8895 / android_kernel_samsung_universal8895.git / commitdiff