--- /dev/null
+/*
+ * Allwinner sunxi resistive touchscreen controller driver
+ *
+ * Copyright (C) 2013 - 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.
+ */
+
+/*
+ * The sun4i-ts controller is capable of detecting a second touch, but when a
+ * second touch is present then the accuracy becomes so bad the reported touch
+ * location is not useable.
+ *
+ * The original android driver contains some complicated heuristics using the
+ * aprox. distance between the 2 touches to see if the user is making a pinch
+ * open / close movement, and then reports emulated multi-touch events around
+ * the last touch coordinate (as the dual-touch coordinates are worthless).
+ *
+ * These kinds of heuristics are just asking for trouble (and don't belong
+ * in the kernel). So this driver offers straight forward, reliable single
+ * touch functionality only.
+ */
+
+#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/slab.h>
+
+#define TP_CTRL0 0x00
+#define TP_CTRL1 0x04
+#define TP_CTRL2 0x08
+#define TP_CTRL3 0x0c
+#define TP_INT_FIFOC 0x10
+#define TP_INT_FIFOS 0x14
+#define TP_TPR 0x18
+#define TP_CDAT 0x1c
+#define TEMP_DATA 0x20
+#define TP_DATA 0x24
+
+/* TP_CTRL0 bits */
+#define ADC_FIRST_DLY(x) ((x) << 24) /* 8 bits */
+#define ADC_FIRST_DLY_MODE(x) ((x) << 23)
+#define ADC_CLK_SEL(x) ((x) << 22)
+#define ADC_CLK_DIV(x) ((x) << 20) /* 3 bits */
+#define FS_DIV(x) ((x) << 16) /* 4 bits */
+#define T_ACQ(x) ((x) << 0) /* 16 bits */
+
+/* TP_CTRL1 bits */
+#define STYLUS_UP_DEBOUN(x) ((x) << 12) /* 8 bits */
+#define STYLUS_UP_DEBOUN_EN(x) ((x) << 9)
+#define TOUCH_PAN_CALI_EN(x) ((x) << 6)
+#define TP_DUAL_EN(x) ((x) << 5)
+#define TP_MODE_EN(x) ((x) << 4)
+#define TP_ADC_SELECT(x) ((x) << 3)
+#define ADC_CHAN_SELECT(x) ((x) << 0) /* 3 bits */
+
+/* TP_CTRL2 bits */
+#define TP_SENSITIVE_ADJUST(x) ((x) << 28) /* 4 bits */
+#define TP_MODE_SELECT(x) ((x) << 26) /* 2 bits */
+#define PRE_MEA_EN(x) ((x) << 24)
+#define PRE_MEA_THRE_CNT(x) ((x) << 0) /* 24 bits */
+
+/* TP_CTRL3 bits */
+#define FILTER_EN(x) ((x) << 2)
+#define FILTER_TYPE(x) ((x) << 0) /* 2 bits */
+
+/* TP_INT_FIFOC irq and fifo mask / control bits */
+#define TEMP_IRQ_EN(x) ((x) << 18)
+#define OVERRUN_IRQ_EN(x) ((x) << 17)
+#define DATA_IRQ_EN(x) ((x) << 16)
+#define TP_DATA_XY_CHANGE(x) ((x) << 13)
+#define FIFO_TRIG(x) ((x) << 8) /* 5 bits */
+#define DATA_DRQ_EN(x) ((x) << 7)
+#define FIFO_FLUSH(x) ((x) << 4)
+#define TP_UP_IRQ_EN(x) ((x) << 1)
+#define TP_DOWN_IRQ_EN(x) ((x) << 0)
+
+/* TP_INT_FIFOS irq and fifo status bits */
+#define TEMP_DATA_PENDING BIT(18)
+#define FIFO_OVERRUN_PENDING BIT(17)
+#define FIFO_DATA_PENDING BIT(16)
+#define TP_IDLE_FLG BIT(2)
+#define TP_UP_PENDING BIT(1)
+#define TP_DOWN_PENDING BIT(0)
+
+/* TP_TPR bits */
+#define TEMP_ENABLE(x) ((x) << 16)
+#define TEMP_PERIOD(x) ((x) << 0) /* t = x * 256 * 16 / clkin */
+
+struct sun4i_ts_data {
+ struct device *dev;
+ struct input_dev *input;
+ void __iomem *base;
+ unsigned int irq;
+ bool ignore_fifo_data;
+};
+
+static irqreturn_t sun4i_ts_irq(int irq, void *dev_id)
+{
+ struct sun4i_ts_data *ts = dev_id;
+ u32 reg_val, x, y;
+
+ reg_val = readl(ts->base + TP_INT_FIFOS);
+
+ if (reg_val & FIFO_DATA_PENDING) {
+ x = readl(ts->base + TP_DATA);
+ y = readl(ts->base + TP_DATA);
+ /* The 1st location reported after an up event is unreliable */
+ if (!ts->ignore_fifo_data) {
+ input_report_abs(ts->input, ABS_X, x);
+ input_report_abs(ts->input, ABS_Y, y);
+ /*
+ * The hardware has a separate down status bit, but
+ * that gets set before we get the first location,
+ * resulting in reporting a click on the old location.
+ */
+ input_report_key(ts->input, BTN_TOUCH, 1);
+ input_sync(ts->input);
+ } else {
+ ts->ignore_fifo_data = false;
+ }
+ }
+
+ if (reg_val & TP_UP_PENDING) {
+ ts->ignore_fifo_data = true;
+ input_report_key(ts->input, BTN_TOUCH, 0);
+ input_sync(ts->input);
+ }
+
+ writel(reg_val, ts->base + TP_INT_FIFOS);
+
+ return IRQ_HANDLED;
+}
+
+static int sun4i_ts_open(struct input_dev *dev)
+{
+ struct sun4i_ts_data *ts = input_get_drvdata(dev);
+
+ /* Flush, set trig level to 1, enable data and up irqs */
+ writel(DATA_IRQ_EN(1) | FIFO_TRIG(1) | FIFO_FLUSH(1) | TP_UP_IRQ_EN(1),
+ ts->base + TP_INT_FIFOC);
+
+ return 0;
+}
+
+static void sun4i_ts_close(struct input_dev *dev)
+{
+ struct sun4i_ts_data *ts = input_get_drvdata(dev);
+
+ /* Deactivate all IRQs */
+ writel(0, ts->base + TP_INT_FIFOC);
+}
+
+static int sun4i_ts_probe(struct platform_device *pdev)
+{
+ struct sun4i_ts_data *ts;
+ struct device *dev = &pdev->dev;
+ int error;
+
+ ts = devm_kzalloc(dev, sizeof(struct sun4i_ts_data), GFP_KERNEL);
+ if (!ts)
+ return -ENOMEM;
+
+ ts->dev = dev;
+ ts->ignore_fifo_data = true;
+
+ ts->input = devm_input_allocate_device(dev);
+ if (!ts->input)
+ return -ENOMEM;
+
+ ts->input->name = pdev->name;
+ ts->input->phys = "sun4i_ts/input0";
+ ts->input->open = sun4i_ts_open;
+ ts->input->close = sun4i_ts_close;
+ ts->input->id.bustype = BUS_HOST;
+ ts->input->id.vendor = 0x0001;
+ ts->input->id.product = 0x0001;
+ ts->input->id.version = 0x0100;
+ ts->input->evbit[0] = BIT(EV_SYN) | BIT(EV_KEY) | BIT(EV_ABS);
+ __set_bit(BTN_TOUCH, ts->input->keybit);
+ input_set_abs_params(ts->input, ABS_X, 0, 4095, 0, 0);
+ input_set_abs_params(ts->input, ABS_Y, 0, 4095, 0, 0);
+ input_set_drvdata(ts->input, ts);
+
+ ts->base = devm_ioremap_resource(dev,
+ platform_get_resource(pdev, IORESOURCE_MEM, 0));
+ if (IS_ERR(ts->base))
+ return PTR_ERR(ts->base);
+
+ ts->irq = platform_get_irq(pdev, 0);
+ error = devm_request_irq(dev, ts->irq, sun4i_ts_irq, 0, "sun4i-ts", ts);
+ if (error)
+ return error;
+
+ /*
+ * Select HOSC clk, clkin = clk / 6, adc samplefreq = clkin / 8192,
+ * t_acq = clkin / (16 * 64)
+ */
+ writel(ADC_CLK_SEL(0) | ADC_CLK_DIV(2) | FS_DIV(7) | T_ACQ(63),
+ ts->base + TP_CTRL0);
+
+ /*
+ * sensitive_adjust = 15 : max, which is not all that sensitive,
+ * tp_mode = 0 : only x and y coordinates, as we don't use dual touch
+ */
+ writel(TP_SENSITIVE_ADJUST(15) | TP_MODE_SELECT(0),
+ ts->base + TP_CTRL2);
+
+ /* Enable median filter, type 1 : 5/3 */
+ writel(FILTER_EN(1) | FILTER_TYPE(1), ts->base + TP_CTRL3);
+
+ /* Enable temperature measurement, period 1953 (2 seconds) */
+ writel(TEMP_ENABLE(1) | TEMP_PERIOD(1953), ts->base + TP_TPR);
+
+ /*
+ * Set stylus up debounce to aprox 10 ms, enable debounce, and
+ * finally enable tp mode.
+ */
+ writel(STYLUS_UP_DEBOUN(5) | STYLUS_UP_DEBOUN_EN(1) | TP_MODE_EN(1),
+ ts->base + TP_CTRL1);
+
+ error = input_register_device(ts->input);
+ if (error)
+ return error;
+
+ platform_set_drvdata(pdev, ts);
+ return 0;
+}
+
+static const struct of_device_id sun4i_ts_of_match[] = {
+ { .compatible = "allwinner,sun4i-a10-ts", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sun4i_ts_of_match);
+
+static struct platform_driver sun4i_ts_driver = {
+ .driver = {
+ .owner = THIS_MODULE,
+ .name = "sun4i-ts",
+ .of_match_table = of_match_ptr(sun4i_ts_of_match),
+ },
+ .probe = sun4i_ts_probe,
+};
+
+module_platform_driver(sun4i_ts_driver);
+
+MODULE_DESCRIPTION("Allwinner sun4i resistive touchscreen controller driver");
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_LICENSE("GPL");
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