rfc input/touch: LPC32xx: Introduce touch driver for the LPC32xx

From: Kevin Wells <[email protected]>

This patch set introduces support for the LPC32xx touchscreen controller driver. The LPC32xx touchscreen controller supports automated event detection and X/Y data conversion for resistive touchscreens.

Signed-off-by Kevin Wells <[email protected]>

Signed-off-by Durgesh Pattamatta <[email protected]>

---
 drivers/input/touchscreen/Kconfig      |   10 +
 drivers/input/touchscreen/Makefile     |    1 +
 drivers/input/touchscreen/lpc32xx_ts.c |  365 ++++++++++++++++++++++++++++++++
 3 files changed, 376 insertions(+), 0 deletions(-)
 create mode 100644 drivers/input/touchscreen/lpc32xx_ts.c

drivers/input/touchscreen/Kconfig +10 -0

index 61f3518..f74b6eb 100644
@@ -214,6 +214,16 @@ config TOUCHSCREEN_WACOM_W8001
 	  To compile this driver as a module, choose M here: the
 	  module will be called wacom_w8001.
 
+config TOUCHSCREEN_LPC32XX
+	tristate "LPC32XX touchscreen controller"
+	depends on ARCH_LPC32XX
+	help
+	  Say Y here if you have a LPC32XX device and want
+	  to support the built-in touchscreen.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called lpc32xx_ts.
+
 config TOUCHSCREEN_MCS5000
 	tristate "MELFAS MCS-5000 touchscreen"
 	depends on I2C

drivers/input/touchscreen/Makefile +1 -0

index bd6f30b..595275d 100644
@@ -23,6 +23,7 @@ obj-$(CONFIG_TOUCHSCREEN_EETI)		+= eeti_ts.o
 obj-$(CONFIG_TOUCHSCREEN_ELO)		+= elo.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_INEXIO)	+= inexio.o
+obj-$(CONFIG_TOUCHSCREEN_LPC32XX)	+= lpc32xx_ts.o
 obj-$(CONFIG_TOUCHSCREEN_MC13783)	+= mc13783_ts.o
 obj-$(CONFIG_TOUCHSCREEN_MCS5000)	+= mcs5000_ts.o
 obj-$(CONFIG_TOUCHSCREEN_MIGOR)		+= migor_ts.o

drivers/input/touchscreen/lpc32xx_ts.c new file +128 -0

new file mode 100644
index 0000000..ebb8f28
@@ -0,0 +1,365 @@
+/*
+ * LPC32xx built-in touchscreen driver
+ *
+ * Copyright (C) 2010 NXP Semiconductors
+ *
+ * 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.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+
+/*
+ * Touchscreen controller register offsets
+ */
+#define TSC_STAT			0x00
+#define TSC_SEL				0x04
+#define TSC_CON				0x08
+#define TSC_FIFO			0x0C
+#define TSC_DTR				0x10
+#define TSC_RTR				0x14
+#define TSC_UTR				0x18
+#define TSC_TTR				0x1C
+#define TSC_DXP				0x20
+#define TSC_MIN_X			0x24
+#define TSC_MAX_X			0x28
+#define TSC_MIN_Y			0x2C
+#define TSC_MAX_Y			0x30
+#define TSC_AUX_UTR			0x34
+#define TSC_AUX_MIN			0x38
+#define TSC_AUX_MAX			0x3C
+
+#define TSC_STAT_FIFO_OVRRN		(1 << 8)
+#define TSC_STAT_FIFO_EMPTY		(1 << 7)
+
+#define TSC_SEL_DEFVAL			0x0284
+
+#define TSC_ADCCON_IRQ_TO_FIFO_4	(0x1 << 11)
+#define TSC_ADCCON_X_SAMPLE_SIZE(s)	((10 - (s)) << 7)
+#define TSC_ADCCON_Y_SAMPLE_SIZE(s)	((10 - (s)) << 4)
+#define TSC_ADCCON_POWER_UP		(1 << 2)
+#define TSC_ADCCON_AUTO_EN		(1 << 0)
+
+#define TSC_FIFO_TS_P_LEVEL		(1 << 31)
+#define TSC_FIFO_NORMALIZE_X_VAL(x)	(((x) & 0x03FF0000) >> 16)
+#define TSC_FIFO_NORMALIZE_Y_VAL(y)	((y) & 0x000003FF)
+
+#define TSC_ADCDAT_VALUE_MASK		0x000003FF
+
+#define TSC_MIN_XY_VAL			0x0
+#define TSC_MAX_XY_VAL			0x3FF
+
+#define MOD_NAME "ts-lpc32xx"
+
+#define tsc_readl(dev, reg) \
+	__raw_readl((dev)->tsc_base + (reg))
+#define tsc_writel(dev, reg, val) \
+	__raw_writel((val), (dev)->tsc_base + (reg))
+
+struct lpc32xx_tsc {
+	struct input_dev *dev;
+	void __iomem *tsc_base;
+	int irq;
+	struct clk *clk;
+};
+
+static void lpc32xx_fifo_clear(struct lpc32xx_tsc *tsc)
+{
+	while (!(tsc_readl(tsc, TSC_STAT) & TSC_STAT_FIFO_EMPTY))
+		tsc_readl(tsc, TSC_FIFO);
+}
+
+static irqreturn_t lpc32xx_ts_interrupt(int irq, void *dev_id)
+{
+	u32 tmp, rv[4], xs[4], ys[4];
+	int idx;
+	struct lpc32xx_tsc *tsc = dev_id;
+	struct input_dev *input = tsc->dev;
+
+	tmp = tsc_readl(tsc, TSC_STAT);
+
+	if (tmp & TSC_STAT_FIFO_OVRRN) {
+		/* FIFO overflow - throw away samples */
+		lpc32xx_fifo_clear(tsc);
+		return IRQ_HANDLED;
+	}
+
+	/*
+	 * Gather and normalize 4 samples. Pen-up events may have less
+	 * than 4 samples, but its ok to pop 4 and let the last sample
+	 * pen status check drop the samples.
+	 */
+	idx = 0;
+	while ((idx < 4) &&
+		(!(tsc_readl(tsc, TSC_STAT) & TSC_STAT_FIFO_EMPTY))) {
+		tmp = tsc_readl(tsc, TSC_FIFO);
+		xs[idx] = TSC_ADCDAT_VALUE_MASK -
+			TSC_FIFO_NORMALIZE_X_VAL(tmp);
+		ys[idx] = TSC_ADCDAT_VALUE_MASK -
+			TSC_FIFO_NORMALIZE_Y_VAL(tmp);
+		rv[idx] = tmp;
+		idx++;
+	}
+
+	/* Data is only valid if pen is still down in last sample */
+	if ((!(rv[3] & TSC_FIFO_TS_P_LEVEL)) && (idx == 4)) {
+		/* Use average of 2nd and 3rd sample for position */
+		input_report_abs(input, ABS_X, ((xs[1] + xs[2]) / 2));
+		input_report_abs(input, ABS_Y, ((ys[1] + ys[2]) / 2));
+		input_report_key(input, BTN_TOUCH, 1);
+	} else
+		input_report_key(input, BTN_TOUCH, 0);
+
+	input_sync(input);
+

drivers/input/touchscreen/lpc32xx_ts.c new file +106 -0

+	u32 tmp;
+
+	tmp = tsc_readl(tsc, TSC_CON) & ~TSC_ADCCON_POWER_UP;
+
+	/* Set the TSC FIFO depth to 4 samples @ 10-bits per sample (max) */
+	tmp = (TSC_ADCCON_IRQ_TO_FIFO_4 |
+		TSC_ADCCON_X_SAMPLE_SIZE(10) |
+		TSC_ADCCON_Y_SAMPLE_SIZE(10));
+	tsc_writel(tsc, TSC_CON, tmp);
+
+	/* These values are all preset */
+	tsc_writel(tsc, TSC_SEL, TSC_SEL_DEFVAL);
+	tsc_writel(tsc, TSC_MIN_X, TSC_MIN_XY_VAL);
+	tsc_writel(tsc, TSC_MAX_X, TSC_MAX_XY_VAL);
+	tsc_writel(tsc, TSC_MIN_Y, TSC_MIN_XY_VAL);
+	tsc_writel(tsc, TSC_MAX_Y, TSC_MAX_XY_VAL);
+
+	/* Aux support is not used */
+	tsc_writel(tsc, TSC_AUX_UTR, 0);
+	tsc_writel(tsc, TSC_AUX_MIN, 0);
+	tsc_writel(tsc, TSC_AUX_MAX, 0);
+
+	/*
+	 * Set sample rate to about 240Hz per X/Y pair. A single measurement
+	 * consists of 4 pairs which gives about a 60Hz sample rate based on
+	 * a stable 32768Hz clock source. Values are in clocks.
+	 * Rate is (32768 / (RTR + XCONV + RTR + YCONV + DXP + TTR + UTR) / 4
+	 */
+	tsc_writel(tsc, TSC_RTR, 0x2);
+	tsc_writel(tsc, TSC_DTR, 0x2);
+	tsc_writel(tsc, TSC_TTR, 0x10);
+	tsc_writel(tsc, TSC_DXP, 0x4);
+	tsc_writel(tsc, TSC_UTR, 88);
+
+	lpc32xx_fifo_clear(tsc);
+
+	/* Enable automatic ts event capture */
+	tsc_writel(tsc, TSC_CON, tmp | TSC_ADCCON_AUTO_EN);
+}
+
+static int __devinit lpc32xx_ts_probe(struct platform_device *pdev)
+{
+	struct lpc32xx_tsc *tsc;
+	struct resource *res;
+	resource_size_t size;
+	int retval;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "Can't get memory resource\n");
+		return -ENOENT;
+	}
+
+	retval = platform_get_irq(pdev, 0);
+	if (retval < 0) {
+		dev_err(&pdev->dev, "Can't get interrupt resource\n");
+		return retval;
+	}
+
+	tsc = devm_kzalloc(&pdev->dev, sizeof(*tsc), GFP_KERNEL);
+	if (unlikely(!tsc)) {
+		dev_err(&pdev->dev, "failed allocating memory\n");
+		return -ENOMEM;
+	}
+	tsc->irq = retval;
+
+	size = resource_size(res);
+
+	if (!devm_request_mem_region(&pdev->dev, res->start, size,
+				     pdev->name)) {
+		dev_err(&pdev->dev, "TSC registers are not free\n");
+		return -EBUSY;
+	}
+
+	tsc->tsc_base = devm_ioremap(&pdev->dev, res->start, size);
+	if (!tsc->tsc_base) {
+		dev_err(&pdev->dev, "Can't map memory\n");
+		return -ENOMEM;
+	}
+
+	tsc->dev = input_allocate_device();
+	if (!tsc->dev) {
+		dev_err(&pdev->dev, "failed allocating input device\n");
+		return -ENOMEM;
+	}
+
+	tsc->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(tsc->clk)) {
+		dev_err(&pdev->dev, "failed getting clock\n");
+		retval = -ENOENT;
+		goto err_no_clk;
+	}
+
+	clk_enable(tsc->clk);
+	setup_tsc(tsc);
+
+	platform_set_drvdata(pdev, tsc);
+
+	tsc->dev->name = MOD_NAME;
+	tsc->dev->phys = "lpc32xx/input0";
+	tsc->dev->id.bustype = BUS_HOST;
+	tsc->dev->id.vendor = 0x0001;
+	tsc->dev->id.product = 0x0002;
+	tsc->dev->id.version = 0x0100;
+	tsc->dev->dev.parent = &pdev->dev;
+

drivers/input/touchscreen/lpc32xx_ts.c new file +5 -0

+	}
+
+	retval = devm_request_irq(&pdev->dev, tsc->irq, lpc32xx_ts_interrupt,
+		IRQF_DISABLED, pdev->name, tsc);
+	if (retval < 0) {

drivers/input/touchscreen/lpc32xx_ts.c new file +16 -0

+
+err_stop_clk:
+	stop_tsc(tsc);
+	clk_disable(tsc->clk);
+	clk_put(tsc->clk);
+
+err_no_clk:
+	input_free_device(tsc->dev);
+
+	return retval;
+}
+
+static int __devexit lpc32xx_ts_remove(struct platform_device *pdev)
+{
+	struct lpc32xx_tsc *tsc = platform_get_drvdata(pdev);
+

drivers/input/touchscreen/lpc32xx_ts.c new file +68 -0

+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int lpc32xx_ts_suspend(struct device *dev)
+{
+	struct lpc32xx_tsc *tsc = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(tsc->irq);
+	else {
+		stop_tsc(tsc);
+		clk_disable(tsc->clk);
+	}
+
+	return 0;
+}
+
+static int lpc32xx_ts_resume(struct device *dev)
+{
+	struct lpc32xx_tsc *tsc = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(tsc->irq);
+	else {
+		clk_enable(tsc->clk);
+		setup_tsc(tsc);
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops lpc32xx_ts_pm_ops = {
+	.suspend	= lpc32xx_ts_suspend,
+	.resume		= lpc32xx_ts_resume,
+};
+#define LPC32XX_TS_PM_OPS (&lpc32xx_ts_pm_ops)
+#else
+#define LPC32XX_TS_PM_OPS NULL
+#endif
+
+static struct platform_driver lpc32xx_ts_driver = {
+	.probe		= lpc32xx_ts_probe,
+	.remove		= __devexit_p(lpc32xx_ts_remove),
+	.driver		= {
+		.name	= MOD_NAME,
+		.owner	= THIS_MODULE,
+		.pm	= LPC32XX_TS_PM_OPS,
+	},
+};
+
+static int __init lpc32xx_ts_init(void)
+{
+	return platform_driver_register(&lpc32xx_ts_driver);
+}
+module_init(lpc32xx_ts_init);
+
+static void __exit lpc32xx_ts_exit(void)
+{
+	platform_driver_unregister(&lpc32xx_ts_driver);
+}
+module_exit(lpc32xx_ts_exit);
+
+MODULE_AUTHOR("Kevin Wells <[email protected]");
+MODULE_DESCRIPTION("LPC32XX TSC Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:lpc32xx_ts");

Signature · 1 line

1.7.1.1

Quoted 6 lines

This patch set introduces support for the LPC32xx touchscreen controller driver. The LPC32xx touchscreen controller supports automated event detection and X/Y data conversion for resistive touchscreens.

Overall looks very nice, a few comments below.

Quoted 4 lines

+
+ ? ? if (input_register_device(tsc->dev)) {
+ ? ? ? ? ? ? dev_err(&pdev->dev, "failed registering input device\n");
+ ? ? ? ? ? ? goto err_stop_clk;

retval is garbage here, you need to do:

? ? ? ?error = input_register_device();
? ? ? ?if (error) {
? ? ? ? ? ? ? ?...
? ? ? ? ? ? ? ?goto err_stop_clk;
? ? ? ?}

I must say that I do not like mixing devm_* with the standard error path unwinding, if we can rely on devm_xxx() calls to take care of everything we should revert to standard error unsinding practice for everythng.

Quoted 9 lines

Quoted 6 lines

This patch set introduces support for the LPC32xx touchscreen controller driver. The LPC32xx touchscreen controller supports automated event detection and X/Y data conversion for resistive touchscreens.

Overall looks very nice, a few comments below.

Thanks for helping review this driver. I'll update and repost once the fixes and changes are finalized.

Quoted 13 lines

Quoted 4 lines

+
+ ? ? if (input_register_device(tsc->dev)) {
+ ? ? ? ? ? ? dev_err(&pdev->dev, "failed registering input device\n");
+ ? ? ? ? ? ? goto err_stop_clk;

retval is garbage here, you need to do:

? ? ? ?error = input_register_device();
? ? ? ?if (error) {
? ? ? ? ? ? ? ?...
? ? ? ? ? ? ? ?goto err_stop_clk;
? ? ? ?}

Quoted 4 lines

I must say that I do not like mixing devm_* with the standard error path unwinding, if we can rely on devm_xxx() calls to take care of everything we should revert to standard error unsinding practice for everythng.

Would it be preferable to just use standard resource functions and error path unwinding (with fixes in _remove too) similar to the other drivers in ./drivers/input?