[RFC 0/1] misc: Add Allwinner Q8 tablet hardware manager

[RFC 0/1] misc: Add Allwinner Q8 tablet hardware manager

[Hans de Goede]

Hi All,

Here is a first RFC for the q8 tablet hw-manager I've been talking
about for a while now.

The touchscreen part is finished, I'll start working on the
accelerometer bits next.

Note that this requires the "of: changesets: Introduce changeset
helper methods" patch from Pantelis. If that is still not upstream
when I'm ready to post a non RFC, I'll post a new version of that
myself.

Regards,

Hans

[RFC] misc: Add Allwinner Q8 tablet hardware manager

[Hans de Goede]

Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets
of which a new batch is produced every few weeks. Each batch uses a
different mix of touchscreen, accelerometer and wifi peripherals.

Given that each batch is different creating a devicetree for each variant
is not desirable. This commit adds a Q8 tablet hardware manager which
auto-detects the touchscreen and accelerometer so that a single generic
dts can be used for these tablets.

The wifi is connected to a discoverable bus (sdio or usb) and will be
autodetected by the mmc resp. usb subsystems.

Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 .../misc/allwinner,sunxi-q8-hardwaremgr.txt        |  52 +++
 drivers/misc/Kconfig                               |  12 +
 drivers/misc/Makefile                              |   1 +
 drivers/misc/q8-hardwaremgr.c                      | 512 +++++++++++++++++++++
 4 files changed, 577 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
 create mode 100644 drivers/misc/q8-hardwaremgr.c

diff --git a/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
new file mode 100644
index 0000000..f428bf5
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
@@ -0,0 +1,52 @@
+Q8 tablet hardware manager
+--------------------------
+
+Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets of
+which a new batch is produced every few weeks. Each batch uses a different
+mix of touchscreen, accelerometer and wifi peripherals.
+
+Given that each batch is different creating a devicetree for each variant is
+not desirable. The Q8 tablet hardware manager bindings are bindings for an os
+module which auto-detects the touchscreen so that a single
+generic dts can be used for these tablets.
+
+The wifi is connected to a discoverable bus and will be autodetected by the os.
+
+Required properties:
+ - compatible         : "allwinner,sunxi-q8-hardwaremgr"
+ - touchscreen        : phandle of a template touchscreen node, this must be a
+		        child node of the touchscreen i2c bus
+
+Optional properties:
+ - touchscreen-supply : regulator phandle for the touchscreen vdd supply
+
+touschreen node required properties:
+ - interrupt-parent   : phandle pointing to the interrupt controller
+			serving the touchscreen interrupt
+ - interrupts         : interrupt specification for the touchscreen interrupt
+ - power-gpios        : Specification for the pin connected to the touchscreen's
+			enable / wake pin. This needs to be driven high to
+			enable the touchscreen controller
+
+Example:
+
+/ {
+	hwmgr {
+		compatible = "allwinner,sunxi-q8-hardwaremgr";
+		touchscreen = <&touchscreen>;
+		touchscreen-supply = <&reg_ldo_io1>;
+	};
+};
+
+&i2c0 {
+	touchscreen: touchscreen@0 {
+		interrupt-parent = <&pio>;
+		interrupts = <1 5 IRQ_TYPE_EDGE_FALLING>; /* PB5 */
+		power-gpios = <&pio 7 1 GPIO_ACTIVE_HIGH>; /* PH1 */
+		/*
+		 * Enabled by sunxi-q8-hardwaremgr if it detects a
+		 * known model touchscreen.
+		 */
+		status = "disabled";
+	};
+};
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index a216b46..c3e7772 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -804,6 +804,18 @@ config PANEL_BOOT_MESSAGE
 	  An empty message will only clear the display at driver init time. Any other
 	  printf()-formatted message is valid with newline and escape codes.
 
+config Q8_HARDWAREMGR
+	tristate "Allwinner Q8 tablet hardware manager"
+	depends on GPIOLIB || COMPILE_TEST
+	depends on I2C
+	depends on OF
+	default	n
+	help
+	  This option enables support for autodetecting the touchscreen
+	  on Allwinner Q8 tablets.
+
+	  If unsure, say N.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 7410c6d..cac76b7 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -57,6 +57,7 @@ obj-$(CONFIG_ECHO)		+= echo/
 obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
 obj-$(CONFIG_CXL_BASE)		+= cxl/
 obj-$(CONFIG_PANEL)             += panel.o
+obj-$(CONFIG_Q8_HARDWAREMGR)    += q8-hardwaremgr.o
 
 lkdtm-$(CONFIG_LKDTM)		+= lkdtm_core.o
 lkdtm-$(CONFIG_LKDTM)		+= lkdtm_bugs.o
diff --git a/drivers/misc/q8-hardwaremgr.c b/drivers/misc/q8-hardwaremgr.c
new file mode 100644
index 0000000..e75625e
--- /dev/null
+++ b/drivers/misc/q8-hardwaremgr.c
@@ -0,0 +1,512 @@
+/*
+ * Allwinner q8 formfactor tablet hardware manager
+ *
+ * Copyright (C) 2016 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.
+ */
+
+#include <asm/unaligned.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+/*
+ * We can detect which touchscreen controller is used automatically,
+ * but some controllers can be wired up differently depending on the
+ * q8 PCB variant used, so they need different firmware files / settings.
+ *
+ * We allow the user to specify a firmware_variant to select a config
+ * from a list of known configs. We also allow overriding each setting
+ * individually.
+ */
+
+static int touchscreen_variant = -1;
+module_param(touchscreen_variant, int, 0444);
+MODULE_PARM_DESC(touchscreen_variant, "Touchscreen variant 0-x, -1 for auto");
+
+static int touchscreen_width = -1;
+module_param(touchscreen_width, int, 0444);
+MODULE_PARM_DESC(touchscreen_width, "Touchscreen width, -1 for auto");
+
+static int touchscreen_height = -1;
+module_param(touchscreen_height, int, 0444);
+MODULE_PARM_DESC(touchscreen_height, "Touchscreen height, -1 for auto");
+
+static int touchscreen_invert_x = -1;
+module_param(touchscreen_invert_x, int, 0444);
+MODULE_PARM_DESC(touchscreen_invert_x, "Touchscreen invert x, -1 for auto");
+
+static int touchscreen_invert_y = -1;
+module_param(touchscreen_invert_y, int, 0444);
+MODULE_PARM_DESC(touchscreen_invert_y, "Touchscreen invert y, -1 for auto");
+
+static int touchscreen_swap_x_y = -1;
+module_param(touchscreen_swap_x_y, int, 0444);
+MODULE_PARM_DESC(touchscreen_swap_x_y, "Touchscreen swap x y, -1 for auto");
+
+static char *touchscreen_fw_name;
+module_param(touchscreen_fw_name, charp, 0444);
+MODULE_PARM_DESC(touchscreen_fw_name, "Touchscreen firmware filename");
+
+#define TOUCHSCREEN_POWER_ON_DELAY	20
+#define SILEAD_REG_ID			0xFC
+#define EKTF2127_RESPONSE		0x52
+#define EKTF2127_REQUEST		0x53
+#define EKTF2127_WIDTH			0x63
+
+enum touchscreen_model {
+	touchscreen_unknown,
+	gsl1680_a082,
+	gsl1680_b482,
+	ektf2127,
+	zet6251,
+};
+
+struct q8_hardwaremgr_data {
+	struct device *dev;
+	bool touchscreen_needs_regulator;
+	enum touchscreen_model touchscreen_model;
+	int touchscreen_addr;
+	int touchscreen_variant;
+	int touchscreen_width;
+	int touchscreen_height;
+	int touchscreen_invert_x;
+	int touchscreen_invert_y;
+	int touchscreen_swap_x_y;
+	const char *touchscreen_compatible;
+	const char *touchscreen_fw_name;
+};
+
+typedef int (*probe_func)(struct q8_hardwaremgr_data *data,
+			  struct i2c_adapter *adap);
+
+#if 0
+	ret = i2c_smbus_xfer(adap, 0x40, 0, I2C_SMBUS_WRITE, 0,
+			     I2C_SMBUS_QUICK, NULL);
+	if (ret < 0)
+		return -ENODEV;
+
+#endif
+
+static int q8_hardwaremgr_probe_touchscreen(struct q8_hardwaremgr_data *data,
+					    struct i2c_adapter *adap)
+{
+	struct i2c_client *client;
+	unsigned char buff[24];
+	__le32 chip_id;
+	int ret;
+
+	msleep(TOUCHSCREEN_POWER_ON_DELAY);
+
+	/* Check for silead touchsceen at addr 0x40 */
+	client = i2c_new_dummy(adap, 0x40);
+	if (!client)
+		return -ENOMEM;
+
+	ret = i2c_smbus_read_i2c_block_data(client, SILEAD_REG_ID,
+					    sizeof(chip_id), (u8 *)&chip_id);
+	if (ret == sizeof(chip_id)) {
+		switch (le32_to_cpu(chip_id)) {
+		case 0xa0820000:
+			data->touchscreen_addr = 0x40;
+			data->touchscreen_compatible = "silead,gsl1680";
+			data->touchscreen_model = gsl1680_a082;
+			dev_info(data->dev, "Found Silead touchscreen ID: 0xa0820000\n");
+			break;
+		case 0xb4820000:
+			data->touchscreen_addr = 0x40;
+			data->touchscreen_compatible = "silead,gsl1680";
+			data->touchscreen_model = gsl1680_b482;
+			dev_info(data->dev, "Found Silead touchscreen ID: 0xb4820000\n");
+			break;
+		default:
+			dev_warn(data->dev, "Found Silead touchscreen with unknown ID: 0x%08x\n",
+				 le32_to_cpu(chip_id));
+		}
+		ret = 0;
+	}
+	i2c_unregister_device(client);
+	if (ret == 0 || ret == -ETIMEDOUT /* Bus stuck bail immediately */)
+		return ret;
+
+	/* Check for Elan eKTF2127 touchsceen at addr 0x15 */
+	client = i2c_new_dummy(adap, 0x15);
+	if (!client)
+		return -ENOMEM;
+
+	do {
+		/* Read hello, ignore data, depends on initial power state */
+		ret = i2c_master_recv(client, buff, 4);
+		if (ret != 4)
+			break;
+
+		/* Request width */
+		buff[0] = EKTF2127_REQUEST;
+		buff[1] = EKTF2127_WIDTH;
+		buff[2] = 0x00;
+		buff[3] = 0x00;
+		ret = i2c_master_send(client, buff, 4);
+		if (ret != 4)
+			break;
+
+		msleep(20);
+
+		/* Read response */
+		ret = i2c_master_recv(client, buff, 4);
+		if (ret != 4)
+			break;
+			
+		if (buff[0] == EKTF2127_RESPONSE && buff[1] == EKTF2127_WIDTH) {
+			data->touchscreen_addr = 0x15;
+			data->touchscreen_compatible = "elan,ektf2127";
+			data->touchscreen_model = ektf2127;
+			dev_info(data->dev, "Found Elan eKTF2127 touchscreen\n");
+			ret = 0;
+		}
+	} while (0);
+	i2c_unregister_device(client);
+	if (ret == 0 || ret == -ETIMEDOUT /* Bus stuck bail immediately */)
+		return ret;
+
+	/* Check for Zeitec zet6251 touchsceen at addr 0x76 */
+	client = i2c_new_dummy(adap, 0x76);
+	if (!client)
+		return -ENOMEM;
+
+	/*
+	 * We only do a simple read finger data packet test, because some
+	 * versions require firmware to be loaded. If not firmware is loaded
+	 * the buffer will be filed with 0xff, so we ignore the contents.
+	 */
+	ret = i2c_master_recv(client, buff, 24);
+	if (ret == 24) {
+		data->touchscreen_addr = 0x76;
+		data->touchscreen_compatible = "zeitec,zet6251";
+		data->touchscreen_model = zet6251;
+		dev_info(data->dev, "Found Zeitec zet6251 touchscreen\n");
+		ret = 0;
+	}
+	i2c_unregister_device(client);
+	if (ret == 0 || ret == -ETIMEDOUT /* Bus stuck bail immediately */)
+		return ret;
+
+	return -ENODEV;
+}
+
+static int q8_hardwaremgr_do_probe(struct q8_hardwaremgr_data *data,
+				   const char *prefix, probe_func func)
+{
+	struct device *dev = data->dev;
+	struct device_node *np;
+	struct i2c_adapter *adap;
+	struct regulator *reg;
+	struct gpio_desc *gpio;
+	int ret = 0;
+
+	np = of_parse_phandle(dev->of_node, prefix, 0);
+	if (!np) {
+		dev_err(dev, "Error %s not set\n", prefix);
+		return -EINVAL;
+	}
+
+	adap = of_get_i2c_adapter_by_node(np->parent);
+	if (!adap) {
+		ret = -EPROBE_DEFER;
+		goto put_node;
+	}
+
+	reg = regulator_get_optional(dev, prefix);
+	if (IS_ERR(reg)) {
+		ret = PTR_ERR(reg);
+		if (ret == -EPROBE_DEFER)
+			goto put_adapter;
+		reg = NULL;
+	}
+
+	gpio = fwnode_get_named_gpiod(&np->fwnode, "power-gpios");
+	if (IS_ERR(gpio)) {
+		ret = PTR_ERR(gpio);
+		if (ret == -EPROBE_DEFER)
+			goto put_reg;
+		gpio = NULL;
+	}
+
+	/* First try with only the power gpio driven high */
+	if (gpio) {
+		ret = gpiod_direction_output(gpio, 1);
+		if (ret)
+			goto put_gpio;
+	}
+
+	dev_info(dev, "Looking for %s without a regulator\n", prefix);
+	ret = func(data, adap);
+	if (ret != 0 && reg) {
+		/* Second try, also enable the regulator */
+		ret = regulator_enable(reg);
+		if (ret)
+			goto restore_gpio;
+
+		dev_info(dev, "Looking for %s with a regulator\n", prefix);
+		ret = func(data, adap);
+		if (ret == 0)
+			data->touchscreen_needs_regulator = true; 
+
+		regulator_disable(reg);
+	}
+	ret = 0; /* Not finding a device is not an error */
+
+restore_gpio:
+	if (gpio)
+		gpiod_direction_output(gpio, 0);
+put_gpio:
+	if (gpio)
+		gpiod_put(gpio);
+put_reg:
+	if (reg)
+		regulator_put(reg);
+put_adapter:
+	i2c_put_adapter(adap);
+
+put_node:
+	of_node_put(np);
+
+	return ret;
+}
+
+static void q8_hardwaremgr_apply_gsl1680_a082_variant(
+	struct q8_hardwaremgr_data *data)
+{
+	if (touchscreen_variant != -1) {
+		data->touchscreen_variant = touchscreen_variant;
+	} else {
+		if (of_machine_is_compatible("allwinner,sun8i-a33"))
+			data->touchscreen_variant = 1;
+		else
+			data->touchscreen_variant = 0;
+	}
+
+	switch (data->touchscreen_variant) {
+	default:
+		dev_warn(data->dev, "Error unknown touchscreen_variant %d using 0\n",
+			 touchscreen_variant);
+		/* Fall through */
+	case 0:
+		data->touchscreen_width = 1024;
+		data->touchscreen_height = 600;
+		data->touchscreen_fw_name = "gsl1680-a082-q8-700.fw";
+		break;
+	case 1:
+		data->touchscreen_width = 480;
+		data->touchscreen_height = 800;
+		data->touchscreen_swap_x_y = 1;
+		data->touchscreen_fw_name = "gsl1680-a082-q8-a70.fw";
+		break;
+	}
+}
+
+static void q8_hardwaremgr_apply_gsl1680_b482_variant(
+	struct q8_hardwaremgr_data *data)
+{
+	if (touchscreen_variant != -1)
+		data->touchscreen_variant = touchscreen_variant;
+
+	switch (data->touchscreen_variant) {
+	default:
+		dev_warn(data->dev, "Error unknown touchscreen_variant %d using 0\n",
+			 touchscreen_variant);
+		/* Fall through */
+	case 0:
+		data->touchscreen_width = 960;
+		data->touchscreen_height = 640;
+		data->touchscreen_fw_name = "gsl1680-b482-q8-d702.fw";
+		break;
+	case 1:
+		data->touchscreen_width = 960;
+		data->touchscreen_height = 640;
+		data->touchscreen_fw_name = "gsl1680-b482-q8-a70.fw";
+		break;
+	}
+}
+
+static void q8_hardwaremgr_issue_gsl1680_warning(
+	struct q8_hardwaremgr_data *data)
+{
+	dev_warn(data->dev, "gsl1680 touchscreen may require kernel cmdline parameters to function properly\n");
+	dev_warn(data->dev, "Try q8_hardwaremgr.touchscreen_invert_x=1 if x coordinates are inverted\n");
+	dev_warn(data->dev, "Try q8_hardwaremgr.touchscreen_variant=%d if coordinates are all over the place\n",
+		 !data->touchscreen_variant);
+
+#define	show(x) \
+	dev_info(data->dev, #x " %d (%s)\n", data->x, \
+		 (x == -1) ? "auto" : "user supplied")
+
+	show(touchscreen_variant);
+	show(touchscreen_width);
+	show(touchscreen_height);
+	show(touchscreen_invert_x);
+	show(touchscreen_invert_y);
+	show(touchscreen_swap_x_y);
+	dev_info(data->dev, "touchscreen_fw_name %s (%s)\n",
+		 data->touchscreen_fw_name,
+		 (touchscreen_fw_name == NULL) ? "auto" : "user supplied");
+#undef show
+}
+
+static void q8_hardwaremgr_apply_touchscreen(struct q8_hardwaremgr_data *data)
+{
+	struct device *dev = data->dev;
+	struct of_changeset cset;
+	struct device_node *np;
+
+	switch (data->touchscreen_model) {
+	case touchscreen_unknown:
+		return;
+	case gsl1680_a082:
+		q8_hardwaremgr_apply_gsl1680_a082_variant(data);
+		break;
+	case gsl1680_b482:
+		q8_hardwaremgr_apply_gsl1680_b482_variant(data);
+		break;
+	case ektf2127:
+	case zet6251:
+		/* These have only 1 variant */
+		break;
+	}
+
+	if (touchscreen_width != -1)
+		data->touchscreen_width = touchscreen_width;
+
+	if (touchscreen_height != -1)
+		data->touchscreen_height = touchscreen_height;
+
+	if (touchscreen_invert_x != -1)
+		data->touchscreen_invert_x = touchscreen_invert_x;
+
+	if (touchscreen_invert_y != -1)
+		data->touchscreen_invert_y = touchscreen_invert_y;
+
+	if (touchscreen_swap_x_y != -1)
+		data->touchscreen_swap_x_y = touchscreen_swap_x_y;
+
+	if (touchscreen_fw_name)
+		data->touchscreen_fw_name = touchscreen_fw_name;
+
+	if (data->touchscreen_model == gsl1680_a082 ||
+	    data->touchscreen_model == gsl1680_b482)
+		q8_hardwaremgr_issue_gsl1680_warning(data);
+
+	np = of_parse_phandle(data->dev->of_node, "touchscreen", 0);
+	/* Never happens already checked in q8_hardwaremgr_do_probe() */
+	if (WARN_ON(!np))
+		return;
+
+	of_changeset_init(&cset);
+	of_changeset_add_property_u32(&cset, np, "reg", data->touchscreen_addr);
+	of_changeset_add_property_string(&cset, np, "compatible",
+					 data->touchscreen_compatible);
+
+	if (data->touchscreen_width)
+		of_changeset_add_property_u32(&cset, np, "touchscreen-size-x",
+					      data->touchscreen_width);
+	if (data->touchscreen_height)
+		of_changeset_add_property_u32(&cset, np, "touchscreen-size-y",
+					      data->touchscreen_height);
+	if (data->touchscreen_invert_x)
+		of_changeset_add_property_bool(&cset, np,
+					       "touchscreen-inverted-x");
+	if (data->touchscreen_invert_y)
+		of_changeset_add_property_bool(&cset, np,
+					       "touchscreen-inverted-y");
+	if (data->touchscreen_swap_x_y)
+		of_changeset_add_property_bool(&cset, np,
+					       "touchscreen-swapped-x-y");
+	if (data->touchscreen_fw_name)
+		of_changeset_add_property_string(&cset, np, "firmware-name",
+						 data->touchscreen_fw_name);
+	if (data->touchscreen_needs_regulator) {
+		struct property *p;
+
+		p = of_find_property(dev->of_node, "touchscreen-supply", NULL);
+		/* Never happens already checked in q8_hardwaremgr_do_probe() */
+		if (WARN_ON(!p))
+			return;
+
+		of_changeset_add_property_copy(&cset, np, "vddio-supply",
+					       p->value, p->length);
+	}
+
+	of_changeset_update_property_string(&cset, np, "status", "okay");
+	of_changeset_apply(&cset);
+
+	of_node_put(np);
+}
+
+static int q8_hardwaremgr_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct q8_hardwaremgr_data *data;
+	int ret = 0;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->dev = &pdev->dev;
+
+	ret = q8_hardwaremgr_do_probe(data, "touchscreen",
+				      q8_hardwaremgr_probe_touchscreen);
+	if (ret)
+		goto error;
+
+	/*
+	 * Our pinctrl may conflict with the pinctrl of the detected devices
+	 * we're adding, so remove it before adding detected devices.
+	 */
+	if (dev->pins) {
+		devm_pinctrl_put(dev->pins->p);
+		devm_kfree(dev, dev->pins);
+		dev->pins = NULL;
+	}
+
+	q8_hardwaremgr_apply_touchscreen(data);
+
+error:
+	kfree(data);
+
+	return ret;
+}
+
+static const struct of_device_id q8_hardwaremgr_of_match[] = {
+	{ .compatible = "allwinner,sunxi-q8-hardwaremgr", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, q8_hardwaremgr_of_match);
+
+static struct platform_driver q8_hardwaremgr_driver = {
+	.driver = {
+		.name	= "q8-hardwaremgr",
+		.of_match_table = of_match_ptr(q8_hardwaremgr_of_match),
+	},
+	.probe	= q8_hardwaremgr_probe,
+};
+
+module_platform_driver(q8_hardwaremgr_driver);
+
+MODULE_DESCRIPTION("Allwinner q8 formfactor tablet hardware manager");
+MODULE_AUTHOR("Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>");
+MODULE_LICENSE("GPL");
-- 
2.9.3

Re: [RFC] misc: Add Allwinner Q8 tablet hardware manager

[Pantelis Antoniou]

Hi Hans,

> On Sep 1, 2016, at 22:08 , Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> 
> Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets
> of which a new batch is produced every few weeks. Each batch uses a
> different mix of touchscreen, accelerometer and wifi peripherals.
> 
> Given that each batch is different creating a devicetree for each variant
> is not desirable. This commit adds a Q8 tablet hardware manager which
> auto-detects the touchscreen and accelerometer so that a single generic
> dts can be used for these tablets.
> 
> The wifi is connected to a discoverable bus (sdio or usb) and will be
> autodetected by the mmc resp. usb subsystems.
> 
> Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
> .../misc/allwinner,sunxi-q8-hardwaremgr.txt        |  52 +++
> drivers/misc/Kconfig                               |  12 +
> drivers/misc/Makefile                              |   1 +
> drivers/misc/q8-hardwaremgr.c                      | 512 +++++++++++++++++++++
> 4 files changed, 577 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
> create mode 100644 drivers/misc/q8-hardwaremgr.c
> 
> diff --git a/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
> new file mode 100644
> index 0000000..f428bf5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
> @@ -0,0 +1,52 @@
> +Q8 tablet hardware manager
> +--------------------------
> +
> +Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets of
> +which a new batch is produced every few weeks. Each batch uses a different
> +mix of touchscreen, accelerometer and wifi peripherals.
> +
> +Given that each batch is different creating a devicetree for each variant is
> +not desirable. The Q8 tablet hardware manager bindings are bindings for an os
> +module which auto-detects the touchscreen so that a single
> +generic dts can be used for these tablets.
> +
> +The wifi is connected to a discoverable bus and will be autodetected by the os.
> +
> +Required properties:
> + - compatible         : "allwinner,sunxi-q8-hardwaremgr"
> + - touchscreen        : phandle of a template touchscreen node, this must be a
> +		        child node of the touchscreen i2c bus
> +
> +Optional properties:
> + - touchscreen-supply : regulator phandle for the touchscreen vdd supply
> +
> +touschreen node required properties:
> + - interrupt-parent   : phandle pointing to the interrupt controller
> +			serving the touchscreen interrupt
> + - interrupts         : interrupt specification for the touchscreen interrupt
> + - power-gpios        : Specification for the pin connected to the touchscreen's
> +			enable / wake pin. This needs to be driven high to
> +			enable the touchscreen controller
> +
> +Example:
> +
> +/ {
> +	hwmgr {
> +		compatible = "allwinner,sunxi-q8-hardwaremgr";
> +		touchscreen = <&touchscreen>;
> +		touchscreen-supply = <&reg_ldo_io1>;
> +	};
> +};
> +
> +&i2c0 {
> +	touchscreen: touchscreen@0 {
> +		interrupt-parent = <&pio>;
> +		interrupts = <1 5 IRQ_TYPE_EDGE_FALLING>; /* PB5 */
> +		power-gpios = <&pio 7 1 GPIO_ACTIVE_HIGH>; /* PH1 */
> +		/*
> +		 * Enabled by sunxi-q8-hardwaremgr if it detects a
> +		 * known model touchscreen.
> +		 */
> +		status = "disabled";
> +	};
> +};
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index a216b46..c3e7772 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -804,6 +804,18 @@ config PANEL_BOOT_MESSAGE
> 	  An empty message will only clear the display at driver init time. Any other
> 	  printf()-formatted message is valid with newline and escape codes.
> 
> +config Q8_HARDWAREMGR
> +	tristate "Allwinner Q8 tablet hardware manager"
> +	depends on GPIOLIB || COMPILE_TEST
> +	depends on I2C
> +	depends on OF
> +	default	n
> +	help
> +	  This option enables support for autodetecting the touchscreen
> +	  on Allwinner Q8 tablets.
> +
> +	  If unsure, say N.
> +
> source "drivers/misc/c2port/Kconfig"
> source "drivers/misc/eeprom/Kconfig"
> source "drivers/misc/cb710/Kconfig"
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index 7410c6d..cac76b7 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -57,6 +57,7 @@ obj-$(CONFIG_ECHO)		+= echo/
> obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
> obj-$(CONFIG_CXL_BASE)		+= cxl/
> obj-$(CONFIG_PANEL)             += panel.o
> +obj-$(CONFIG_Q8_HARDWAREMGR)    += q8-hardwaremgr.o
> 
> lkdtm-$(CONFIG_LKDTM)		+= lkdtm_core.o
> lkdtm-$(CONFIG_LKDTM)		+= lkdtm_bugs.o
> diff --git a/drivers/misc/q8-hardwaremgr.c b/drivers/misc/q8-hardwaremgr.c
> new file mode 100644
> index 0000000..e75625e
> --- /dev/null
> +++ b/drivers/misc/q8-hardwaremgr.c
> @@ -0,0 +1,512 @@
> +/*
> + * Allwinner q8 formfactor tablet hardware manager
> + *
> + * Copyright (C) 2016 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.
> + */
> +
> +#include <asm/unaligned.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +/*
> + * We can detect which touchscreen controller is used automatically,
> + * but some controllers can be wired up differently depending on the
> + * q8 PCB variant used, so they need different firmware files / settings.
> + *
> + * We allow the user to specify a firmware_variant to select a config
> + * from a list of known configs. We also allow overriding each setting
> + * individually.
> + */
> +
> +static int touchscreen_variant = -1;
> +module_param(touchscreen_variant, int, 0444);
> +MODULE_PARM_DESC(touchscreen_variant, "Touchscreen variant 0-x, -1 for auto");
> +
> +static int touchscreen_width = -1;
> +module_param(touchscreen_width, int, 0444);
> +MODULE_PARM_DESC(touchscreen_width, "Touchscreen width, -1 for auto");
> +
> +static int touchscreen_height = -1;
> +module_param(touchscreen_height, int, 0444);
> +MODULE_PARM_DESC(touchscreen_height, "Touchscreen height, -1 for auto");
> +
> +static int touchscreen_invert_x = -1;
> +module_param(touchscreen_invert_x, int, 0444);
> +MODULE_PARM_DESC(touchscreen_invert_x, "Touchscreen invert x, -1 for auto");
> +
> +static int touchscreen_invert_y = -1;
> +module_param(touchscreen_invert_y, int, 0444);
> +MODULE_PARM_DESC(touchscreen_invert_y, "Touchscreen invert y, -1 for auto");
> +
> +static int touchscreen_swap_x_y = -1;
> +module_param(touchscreen_swap_x_y, int, 0444);
> +MODULE_PARM_DESC(touchscreen_swap_x_y, "Touchscreen swap x y, -1 for auto");
> +
> +static char *touchscreen_fw_name;
> +module_param(touchscreen_fw_name, charp, 0444);
> +MODULE_PARM_DESC(touchscreen_fw_name, "Touchscreen firmware filename");
> +
> +#define TOUCHSCREEN_POWER_ON_DELAY	20
> +#define SILEAD_REG_ID			0xFC
> +#define EKTF2127_RESPONSE		0x52
> +#define EKTF2127_REQUEST		0x53
> +#define EKTF2127_WIDTH			0x63
> +
> +enum touchscreen_model {
> +	touchscreen_unknown,
> +	gsl1680_a082,
> +	gsl1680_b482,
> +	ektf2127,
> +	zet6251,
> +};
> +
> +struct q8_hardwaremgr_data {
> +	struct device *dev;
> +	bool touchscreen_needs_regulator;
> +	enum touchscreen_model touchscreen_model;
> +	int touchscreen_addr;
> +	int touchscreen_variant;
> +	int touchscreen_width;
> +	int touchscreen_height;
> +	int touchscreen_invert_x;
> +	int touchscreen_invert_y;
> +	int touchscreen_swap_x_y;
> +	const char *touchscreen_compatible;
> +	const char *touchscreen_fw_name;
> +};
> +
> +typedef int (*probe_func)(struct q8_hardwaremgr_data *data,
> +			  struct i2c_adapter *adap);
> +
> +#if 0
> +	ret = i2c_smbus_xfer(adap, 0x40, 0, I2C_SMBUS_WRITE, 0,
> +			     I2C_SMBUS_QUICK, NULL);
> +	if (ret < 0)
> +		return -ENODEV;
> +
> +#endif
> +

^^^ crud?

> +static int q8_hardwaremgr_probe_touchscreen(struct q8_hardwaremgr_data *data,
> +					    struct i2c_adapter *adap)
> +{
> +	struct i2c_client *client;
> +	unsigned char buff[24];
> +	__le32 chip_id;
> +	int ret;
> +
> +	msleep(TOUCHSCREEN_POWER_ON_DELAY);
> +
> +	/* Check for silead touchsceen at addr 0x40 */
> +	client = i2c_new_dummy(adap, 0x40);
> +	if (!client)
> +		return -ENOMEM;
> +
> +	ret = i2c_smbus_read_i2c_block_data(client, SILEAD_REG_ID,
> +					    sizeof(chip_id), (u8 *)&chip_id);
> +	if (ret == sizeof(chip_id)) {
> +		switch (le32_to_cpu(chip_id)) {
> +		case 0xa0820000:
> +			data->touchscreen_addr = 0x40;
> +			data->touchscreen_compatible = "silead,gsl1680";
> +			data->touchscreen_model = gsl1680_a082;
> +			dev_info(data->dev, "Found Silead touchscreen ID: 0xa0820000\n");
> +			break;
> +		case 0xb4820000:
> +			data->touchscreen_addr = 0x40;
> +			data->touchscreen_compatible = "silead,gsl1680";
> +			data->touchscreen_model = gsl1680_b482;
> +			dev_info(data->dev, "Found Silead touchscreen ID: 0xb4820000\n");
> +			break;

> +		default:
> +			dev_warn(data->dev, "Found Silead touchscreen with unknown ID: 0x%08x\n",
> +				 le32_to_cpu(chip_id));
> +		}
> +		ret = 0;
> +	}
> +	i2c_unregister_device(client);
> +	if (ret == 0 || ret == -ETIMEDOUT /* Bus stuck bail immediately */)
> +		return ret;
> +
> +	/* Check for Elan eKTF2127 touchsceen at addr 0x15 */
> +	client = i2c_new_dummy(adap, 0x15);
> +	if (!client)
> +		return -ENOMEM;
> +
> +	do {
> +		/* Read hello, ignore data, depends on initial power state */
> +		ret = i2c_master_recv(client, buff, 4);
> +		if (ret != 4)
> +			break;
> +
> +		/* Request width */
> +		buff[0] = EKTF2127_REQUEST;
> +		buff[1] = EKTF2127_WIDTH;
> +		buff[2] = 0x00;
> +		buff[3] = 0x00;
> +		ret = i2c_master_send(client, buff, 4);
> +		if (ret != 4)
> +			break;
> +
> +		msleep(20);
> +
> +		/* Read response */
> +		ret = i2c_master_recv(client, buff, 4);
> +		if (ret != 4)
> +			break;
> +			
> +		if (buff[0] == EKTF2127_RESPONSE && buff[1] == EKTF2127_WIDTH) {
> +			data->touchscreen_addr = 0x15;
> +			data->touchscreen_compatible = "elan,ektf2127";
> +			data->touchscreen_model = ektf2127;
> +			dev_info(data->dev, "Found Elan eKTF2127 touchscreen\n");
> +			ret = 0;
> +		}
> +	} while (0);
> +	i2c_unregister_device(client);
> +	if (ret == 0 || ret == -ETIMEDOUT /* Bus stuck bail immediately */)
> +		return ret;
> +
> +	/* Check for Zeitec zet6251 touchsceen at addr 0x76 */
> +	client = i2c_new_dummy(adap, 0x76);
> +	if (!client)
> +		return -ENOMEM;
> +
> +	/*
> +	 * We only do a simple read finger data packet test, because some
> +	 * versions require firmware to be loaded. If not firmware is loaded
> +	 * the buffer will be filed with 0xff, so we ignore the contents.
> +	 */
> +	ret = i2c_master_recv(client, buff, 24);
> +	if (ret == 24) {
> +		data->touchscreen_addr = 0x76;
> +		data->touchscreen_compatible = "zeitec,zet6251";
> +		data->touchscreen_model = zet6251;
> +		dev_info(data->dev, "Found Zeitec zet6251 touchscreen\n");
> +		ret = 0;
> +	}

I can understand having a switch here since it’s quite complicated but it would be better to
have a structure that defines them i.e.

struct touchscreen_detect_data {
	u32 chip_id;
	int addr;
	const char *compatible;
	enum touchscreen_model model;
	
};

static const struct touchscreen_detect_data ts_detect_data[] = {
	{
		.chip_id = 0xa0820000,
		.addr = 0x40,
		.compatible = “silead,gsl1680”,
		.model = gsl1680_a082,
	}, ...
};
 
And so on, and restructuring by having different paths by touchscreen model type.


> +	i2c_unregister_device(client);
> +	if (ret == 0 || ret == -ETIMEDOUT /* Bus stuck bail immediately */)
> +		return ret;
> +
> +	return -ENODEV;
> +}
> +
> +static int q8_hardwaremgr_do_probe(struct q8_hardwaremgr_data *data,
> +				   const char *prefix, probe_func func)
> +{
> +	struct device *dev = data->dev;
> +	struct device_node *np;
> +	struct i2c_adapter *adap;
> +	struct regulator *reg;
> +	struct gpio_desc *gpio;
> +	int ret = 0;
> +
> +	np = of_parse_phandle(dev->of_node, prefix, 0);
> +	if (!np) {
> +		dev_err(dev, "Error %s not set\n", prefix);
> +		return -EINVAL;
> +	}
> +
> +	adap = of_get_i2c_adapter_by_node(np->parent);
> +	if (!adap) {
> +		ret = -EPROBE_DEFER;
> +		goto put_node;
> +	}
> +
> +	reg = regulator_get_optional(dev, prefix);
> +	if (IS_ERR(reg)) {
> +		ret = PTR_ERR(reg);
> +		if (ret == -EPROBE_DEFER)
> +			goto put_adapter;
> +		reg = NULL;
> +	}
> +
> +	gpio = fwnode_get_named_gpiod(&np->fwnode, "power-gpios");
> +	if (IS_ERR(gpio)) {
> +		ret = PTR_ERR(gpio);
> +		if (ret == -EPROBE_DEFER)
> +			goto put_reg;
> +		gpio = NULL;
> +	}
> +
> +	/* First try with only the power gpio driven high */
> +	if (gpio) {
> +		ret = gpiod_direction_output(gpio, 1);
> +		if (ret)
> +			goto put_gpio;
> +	}
> +
> +	dev_info(dev, "Looking for %s without a regulator\n", prefix);
> +	ret = func(data, adap);
> +	if (ret != 0 && reg) {
> +		/* Second try, also enable the regulator */
> +		ret = regulator_enable(reg);
> +		if (ret)
> +			goto restore_gpio;
> +
> +		dev_info(dev, "Looking for %s with a regulator\n", prefix);
> +		ret = func(data, adap);
> +		if (ret == 0)
> +			data->touchscreen_needs_regulator = true; 
> +
> +		regulator_disable(reg);
> +	}
> +	ret = 0; /* Not finding a device is not an error */
> +
> +restore_gpio:
> +	if (gpio)
> +		gpiod_direction_output(gpio, 0);
> +put_gpio:
> +	if (gpio)
> +		gpiod_put(gpio);
> +put_reg:
> +	if (reg)
> +		regulator_put(reg);
> +put_adapter:
> +	i2c_put_adapter(adap);
> +
> +put_node:
> +	of_node_put(np);
> +
> +	return ret;
> +}
> +
> +static void q8_hardwaremgr_apply_gsl1680_a082_variant(
> +	struct q8_hardwaremgr_data *data)
> +{
> +	if (touchscreen_variant != -1) {
> +		data->touchscreen_variant = touchscreen_variant;
> +	} else {
> +		if (of_machine_is_compatible("allwinner,sun8i-a33"))
> +			data->touchscreen_variant = 1;
> +		else
> +			data->touchscreen_variant = 0;
> +	}
> +
> +	switch (data->touchscreen_variant) {
> +	default:
> +		dev_warn(data->dev, "Error unknown touchscreen_variant %d using 0\n",
> +			 touchscreen_variant);
> +		/* Fall through */
> +	case 0:
> +		data->touchscreen_width = 1024;
> +		data->touchscreen_height = 600;
> +		data->touchscreen_fw_name = "gsl1680-a082-q8-700.fw";
> +		break;
> +	case 1:
> +		data->touchscreen_width = 480;
> +		data->touchscreen_height = 800;
> +		data->touchscreen_swap_x_y = 1;
> +		data->touchscreen_fw_name = "gsl1680-a082-q8-a70.fw";
> +		break;
> +	}
> +}
> +
> +static void q8_hardwaremgr_apply_gsl1680_b482_variant(
> +	struct q8_hardwaremgr_data *data)
> +{
> +	if (touchscreen_variant != -1)
> +		data->touchscreen_variant = touchscreen_variant;
> +
> +	switch (data->touchscreen_variant) {
> +	default:
> +		dev_warn(data->dev, "Error unknown touchscreen_variant %d using 0\n",
> +			 touchscreen_variant);
> +		/* Fall through */
> +	case 0:
> +		data->touchscreen_width = 960;
> +		data->touchscreen_height = 640;
> +		data->touchscreen_fw_name = "gsl1680-b482-q8-d702.fw";
> +		break;
> +	case 1:
> +		data->touchscreen_width = 960;
> +		data->touchscreen_height = 640;
> +		data->touchscreen_fw_name = "gsl1680-b482-q8-a70.fw";
> +		break;
> +	}
> +}
> +
> +static void q8_hardwaremgr_issue_gsl1680_warning(
> +	struct q8_hardwaremgr_data *data)
> +{
> +	dev_warn(data->dev, "gsl1680 touchscreen may require kernel cmdline parameters to function properly\n");
> +	dev_warn(data->dev, "Try q8_hardwaremgr.touchscreen_invert_x=1 if x coordinates are inverted\n");
> +	dev_warn(data->dev, "Try q8_hardwaremgr.touchscreen_variant=%d if coordinates are all over the place\n",
> +		 !data->touchscreen_variant);
> +
> +#define	show(x) \
> +	dev_info(data->dev, #x " %d (%s)\n", data->x, \
> +		 (x == -1) ? "auto" : "user supplied")
> +
> +	show(touchscreen_variant);
> +	show(touchscreen_width);
> +	show(touchscreen_height);
> +	show(touchscreen_invert_x);
> +	show(touchscreen_invert_y);
> +	show(touchscreen_swap_x_y);
> +	dev_info(data->dev, "touchscreen_fw_name %s (%s)\n",
> +		 data->touchscreen_fw_name,
> +		 (touchscreen_fw_name == NULL) ? "auto" : "user supplied");
> +#undef show
> +}
> +
> +static void q8_hardwaremgr_apply_touchscreen(struct q8_hardwaremgr_data *data)
> +{
> +	struct device *dev = data->dev;
> +	struct of_changeset cset;
> +	struct device_node *np;
> +
> +	switch (data->touchscreen_model) {
> +	case touchscreen_unknown:
> +		return;
> +	case gsl1680_a082:
> +		q8_hardwaremgr_apply_gsl1680_a082_variant(data);
> +		break;
> +	case gsl1680_b482:
> +		q8_hardwaremgr_apply_gsl1680_b482_variant(data);
> +		break;
> +	case ektf2127:
> +	case zet6251:
> +		/* These have only 1 variant */
> +		break;
> +	}
> +
> +	if (touchscreen_width != -1)
> +		data->touchscreen_width = touchscreen_width;
> +
> +	if (touchscreen_height != -1)
> +		data->touchscreen_height = touchscreen_height;
> +
> +	if (touchscreen_invert_x != -1)
> +		data->touchscreen_invert_x = touchscreen_invert_x;
> +
> +	if (touchscreen_invert_y != -1)
> +		data->touchscreen_invert_y = touchscreen_invert_y;
> +
> +	if (touchscreen_swap_x_y != -1)
> +		data->touchscreen_swap_x_y = touchscreen_swap_x_y;
> +
> +	if (touchscreen_fw_name)
> +		data->touchscreen_fw_name = touchscreen_fw_name;
> +
> +	if (data->touchscreen_model == gsl1680_a082 ||
> +	    data->touchscreen_model == gsl1680_b482)
> +		q8_hardwaremgr_issue_gsl1680_warning(data);
> +
> +	np = of_parse_phandle(data->dev->of_node, "touchscreen", 0);
> +	/* Never happens already checked in q8_hardwaremgr_do_probe() */
> +	if (WARN_ON(!np))
> +		return;
> +
> +	of_changeset_init(&cset);
> +	of_changeset_add_property_u32(&cset, np, "reg", data->touchscreen_addr);
> +	of_changeset_add_property_string(&cset, np, "compatible",
> +					 data->touchscreen_compatible);
> +
> +	if (data->touchscreen_width)
> +		of_changeset_add_property_u32(&cset, np, "touchscreen-size-x",
> +					      data->touchscreen_width);
> +	if (data->touchscreen_height)
> +		of_changeset_add_property_u32(&cset, np, "touchscreen-size-y",
> +					      data->touchscreen_height);
> +	if (data->touchscreen_invert_x)
> +		of_changeset_add_property_bool(&cset, np,
> +					       "touchscreen-inverted-x");
> +	if (data->touchscreen_invert_y)
> +		of_changeset_add_property_bool(&cset, np,
> +					       "touchscreen-inverted-y");
> +	if (data->touchscreen_swap_x_y)
> +		of_changeset_add_property_bool(&cset, np,
> +					       "touchscreen-swapped-x-y");
> +	if (data->touchscreen_fw_name)
> +		of_changeset_add_property_string(&cset, np, "firmware-name",
> +						 data->touchscreen_fw_name);
> +	if (data->touchscreen_needs_regulator) {
> +		struct property *p;
> +
> +		p = of_find_property(dev->of_node, "touchscreen-supply", NULL);
> +		/* Never happens already checked in q8_hardwaremgr_do_probe() */
> +		if (WARN_ON(!p))
> +			return;
> +
> +		of_changeset_add_property_copy(&cset, np, "vddio-supply",
> +					       p->value, p->length);
> +	}
> +
> +	of_changeset_update_property_string(&cset, np, "status", "okay");
> +	of_changeset_apply(&cset);
> +
> +	of_node_put(np);
> +}
> +
> +static int q8_hardwaremgr_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct q8_hardwaremgr_data *data;
> +	int ret = 0;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->dev = &pdev->dev;
> +
> +	ret = q8_hardwaremgr_do_probe(data, "touchscreen",
> +				      q8_hardwaremgr_probe_touchscreen);
> +	if (ret)
> +		goto error;
> +
> +	/*
> +	 * Our pinctrl may conflict with the pinctrl of the detected devices
> +	 * we're adding, so remove it before adding detected devices.
> +	 */
> +	if (dev->pins) {
> +		devm_pinctrl_put(dev->pins->p);
> +		devm_kfree(dev, dev->pins);
> +		dev->pins = NULL;
> +	}
> +

Hmm, that’s weird for sure. How can it happen?

> +	q8_hardwaremgr_apply_touchscreen(data);
> +
> +error:
> +	kfree(data);
> +
> +	return ret;
> +}
> +
> +static const struct of_device_id q8_hardwaremgr_of_match[] = {
> +	{ .compatible = "allwinner,sunxi-q8-hardwaremgr", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, q8_hardwaremgr_of_match);
> +
> +static struct platform_driver q8_hardwaremgr_driver = {
> +	.driver = {
> +		.name	= "q8-hardwaremgr",
> +		.of_match_table = of_match_ptr(q8_hardwaremgr_of_match),
> +	},
> +	.probe	= q8_hardwaremgr_probe,
> +};
> +
> +module_platform_driver(q8_hardwaremgr_driver);
> +
> +MODULE_DESCRIPTION("Allwinner q8 formfactor tablet hardware manager");
> +MODULE_AUTHOR("Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>");
> +MODULE_LICENSE("GPL");
> -- 
> 2.9.3
> 

Regards

— Pantelis

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Re: Re: [RFC] misc: Add Allwinner Q8 tablet hardware manager

[Hans de Goede]

Hi,

On 09-09-16 21:13, Pantelis Antoniou wrote:
> Hi Hans,
>
>> On Sep 1, 2016, at 22:08 , Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
>>
>> Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets
>> of which a new batch is produced every few weeks. Each batch uses a
>> different mix of touchscreen, accelerometer and wifi peripherals.
>>
>> Given that each batch is different creating a devicetree for each variant
>> is not desirable. This commit adds a Q8 tablet hardware manager which
>> auto-detects the touchscreen and accelerometer so that a single generic
>> dts can be used for these tablets.
>>
>> The wifi is connected to a discoverable bus (sdio or usb) and will be
>> autodetected by the mmc resp. usb subsystems.
>>
>> Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> ---
>> .../misc/allwinner,sunxi-q8-hardwaremgr.txt        |  52 +++
>> drivers/misc/Kconfig                               |  12 +
>> drivers/misc/Makefile                              |   1 +
>> drivers/misc/q8-hardwaremgr.c                      | 512 +++++++++++++++++++++
>> 4 files changed, 577 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
>> create mode 100644 drivers/misc/q8-hardwaremgr.c
>>
>> diff --git a/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
>> new file mode 100644
>> index 0000000..f428bf5
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
>> @@ -0,0 +1,52 @@
>> +Q8 tablet hardware manager
>> +--------------------------
>> +
>> +Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets of
>> +which a new batch is produced every few weeks. Each batch uses a different
>> +mix of touchscreen, accelerometer and wifi peripherals.
>> +
>> +Given that each batch is different creating a devicetree for each variant is
>> +not desirable. The Q8 tablet hardware manager bindings are bindings for an os
>> +module which auto-detects the touchscreen so that a single
>> +generic dts can be used for these tablets.
>> +
>> +The wifi is connected to a discoverable bus and will be autodetected by the os.
>> +
>> +Required properties:
>> + - compatible         : "allwinner,sunxi-q8-hardwaremgr"
>> + - touchscreen        : phandle of a template touchscreen node, this must be a
>> +		        child node of the touchscreen i2c bus
>> +
>> +Optional properties:
>> + - touchscreen-supply : regulator phandle for the touchscreen vdd supply
>> +
>> +touschreen node required properties:
>> + - interrupt-parent   : phandle pointing to the interrupt controller
>> +			serving the touchscreen interrupt
>> + - interrupts         : interrupt specification for the touchscreen interrupt
>> + - power-gpios        : Specification for the pin connected to the touchscreen's
>> +			enable / wake pin. This needs to be driven high to
>> +			enable the touchscreen controller
>> +
>> +Example:
>> +
>> +/ {
>> +	hwmgr {
>> +		compatible = "allwinner,sunxi-q8-hardwaremgr";
>> +		touchscreen = <&touchscreen>;
>> +		touchscreen-supply = <&reg_ldo_io1>;
>> +	};
>> +};
>> +
>> +&i2c0 {
>> +	touchscreen: touchscreen@0 {
>> +		interrupt-parent = <&pio>;
>> +		interrupts = <1 5 IRQ_TYPE_EDGE_FALLING>; /* PB5 */
>> +		power-gpios = <&pio 7 1 GPIO_ACTIVE_HIGH>; /* PH1 */
>> +		/*
>> +		 * Enabled by sunxi-q8-hardwaremgr if it detects a
>> +		 * known model touchscreen.
>> +		 */
>> +		status = "disabled";
>> +	};
>> +};
>> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
>> index a216b46..c3e7772 100644
>> --- a/drivers/misc/Kconfig
>> +++ b/drivers/misc/Kconfig
>> @@ -804,6 +804,18 @@ config PANEL_BOOT_MESSAGE
>> 	  An empty message will only clear the display at driver init time. Any other
>> 	  printf()-formatted message is valid with newline and escape codes.
>>
>> +config Q8_HARDWAREMGR
>> +	tristate "Allwinner Q8 tablet hardware manager"
>> +	depends on GPIOLIB || COMPILE_TEST
>> +	depends on I2C
>> +	depends on OF
>> +	default	n
>> +	help
>> +	  This option enables support for autodetecting the touchscreen
>> +	  on Allwinner Q8 tablets.
>> +
>> +	  If unsure, say N.
>> +
>> source "drivers/misc/c2port/Kconfig"
>> source "drivers/misc/eeprom/Kconfig"
>> source "drivers/misc/cb710/Kconfig"
>> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
>> index 7410c6d..cac76b7 100644
>> --- a/drivers/misc/Makefile
>> +++ b/drivers/misc/Makefile
>> @@ -57,6 +57,7 @@ obj-$(CONFIG_ECHO)		+= echo/
>> obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
>> obj-$(CONFIG_CXL_BASE)		+= cxl/
>> obj-$(CONFIG_PANEL)             += panel.o
>> +obj-$(CONFIG_Q8_HARDWAREMGR)    += q8-hardwaremgr.o
>>
>> lkdtm-$(CONFIG_LKDTM)		+= lkdtm_core.o
>> lkdtm-$(CONFIG_LKDTM)		+= lkdtm_bugs.o
>> diff --git a/drivers/misc/q8-hardwaremgr.c b/drivers/misc/q8-hardwaremgr.c
>> new file mode 100644
>> index 0000000..e75625e
>> --- /dev/null
>> +++ b/drivers/misc/q8-hardwaremgr.c
>> @@ -0,0 +1,512 @@
>> +/*
>> + * Allwinner q8 formfactor tablet hardware manager
>> + *
>> + * Copyright (C) 2016 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.
>> + */
>> +
>> +#include <asm/unaligned.h>
>> +#include <linux/delay.h>
>> +#include <linux/err.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/i2c.h>
>> +#include <linux/module.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/slab.h>
>> +
>> +/*
>> + * We can detect which touchscreen controller is used automatically,
>> + * but some controllers can be wired up differently depending on the
>> + * q8 PCB variant used, so they need different firmware files / settings.
>> + *
>> + * We allow the user to specify a firmware_variant to select a config
>> + * from a list of known configs. We also allow overriding each setting
>> + * individually.
>> + */
>> +
>> +static int touchscreen_variant = -1;
>> +module_param(touchscreen_variant, int, 0444);
>> +MODULE_PARM_DESC(touchscreen_variant, "Touchscreen variant 0-x, -1 for auto");
>> +
>> +static int touchscreen_width = -1;
>> +module_param(touchscreen_width, int, 0444);
>> +MODULE_PARM_DESC(touchscreen_width, "Touchscreen width, -1 for auto");
>> +
>> +static int touchscreen_height = -1;
>> +module_param(touchscreen_height, int, 0444);
>> +MODULE_PARM_DESC(touchscreen_height, "Touchscreen height, -1 for auto");
>> +
>> +static int touchscreen_invert_x = -1;
>> +module_param(touchscreen_invert_x, int, 0444);
>> +MODULE_PARM_DESC(touchscreen_invert_x, "Touchscreen invert x, -1 for auto");
>> +
>> +static int touchscreen_invert_y = -1;
>> +module_param(touchscreen_invert_y, int, 0444);
>> +MODULE_PARM_DESC(touchscreen_invert_y, "Touchscreen invert y, -1 for auto");
>> +
>> +static int touchscreen_swap_x_y = -1;
>> +module_param(touchscreen_swap_x_y, int, 0444);
>> +MODULE_PARM_DESC(touchscreen_swap_x_y, "Touchscreen swap x y, -1 for auto");
>> +
>> +static char *touchscreen_fw_name;
>> +module_param(touchscreen_fw_name, charp, 0444);
>> +MODULE_PARM_DESC(touchscreen_fw_name, "Touchscreen firmware filename");
>> +
>> +#define TOUCHSCREEN_POWER_ON_DELAY	20
>> +#define SILEAD_REG_ID			0xFC
>> +#define EKTF2127_RESPONSE		0x52
>> +#define EKTF2127_REQUEST		0x53
>> +#define EKTF2127_WIDTH			0x63
>> +
>> +enum touchscreen_model {
>> +	touchscreen_unknown,
>> +	gsl1680_a082,
>> +	gsl1680_b482,
>> +	ektf2127,
>> +	zet6251,
>> +};
>> +
>> +struct q8_hardwaremgr_data {
>> +	struct device *dev;
>> +	bool touchscreen_needs_regulator;
>> +	enum touchscreen_model touchscreen_model;
>> +	int touchscreen_addr;
>> +	int touchscreen_variant;
>> +	int touchscreen_width;
>> +	int touchscreen_height;
>> +	int touchscreen_invert_x;
>> +	int touchscreen_invert_y;
>> +	int touchscreen_swap_x_y;
>> +	const char *touchscreen_compatible;
>> +	const char *touchscreen_fw_name;
>> +};
>> +
>> +typedef int (*probe_func)(struct q8_hardwaremgr_data *data,
>> +			  struct i2c_adapter *adap);
>> +
>> +#if 0
>> +	ret = i2c_smbus_xfer(adap, 0x40, 0, I2C_SMBUS_WRITE, 0,
>> +			     I2C_SMBUS_QUICK, NULL);
>> +	if (ret < 0)
>> +		return -ENODEV;
>> +
>> +#endif
>> +
>
> ^^^ crud?

Yes, please ignore.

>> +static int q8_hardwaremgr_probe_touchscreen(struct q8_hardwaremgr_data *data,
>> +					    struct i2c_adapter *adap)
>> +{
>> +	struct i2c_client *client;
>> +	unsigned char buff[24];
>> +	__le32 chip_id;
>> +	int ret;
>> +
>> +	msleep(TOUCHSCREEN_POWER_ON_DELAY);
>> +
>> +	/* Check for silead touchsceen at addr 0x40 */
>> +	client = i2c_new_dummy(adap, 0x40);
>> +	if (!client)
>> +		return -ENOMEM;
>> +
>> +	ret = i2c_smbus_read_i2c_block_data(client, SILEAD_REG_ID,
>> +					    sizeof(chip_id), (u8 *)&chip_id);
>> +	if (ret == sizeof(chip_id)) {
>> +		switch (le32_to_cpu(chip_id)) {
>> +		case 0xa0820000:
>> +			data->touchscreen_addr = 0x40;
>> +			data->touchscreen_compatible = "silead,gsl1680";
>> +			data->touchscreen_model = gsl1680_a082;
>> +			dev_info(data->dev, "Found Silead touchscreen ID: 0xa0820000\n");
>> +			break;
>> +		case 0xb4820000:
>> +			data->touchscreen_addr = 0x40;
>> +			data->touchscreen_compatible = "silead,gsl1680";
>> +			data->touchscreen_model = gsl1680_b482;
>> +			dev_info(data->dev, "Found Silead touchscreen ID: 0xb4820000\n");
>> +			break;
>
>> +		default:
>> +			dev_warn(data->dev, "Found Silead touchscreen with unknown ID: 0x%08x\n",
>> +				 le32_to_cpu(chip_id));
>> +		}
>> +		ret = 0;
>> +	}
>> +	i2c_unregister_device(client);
>> +	if (ret == 0 || ret == -ETIMEDOUT /* Bus stuck bail immediately */)
>> +		return ret;
>> +
>> +	/* Check for Elan eKTF2127 touchsceen at addr 0x15 */
>> +	client = i2c_new_dummy(adap, 0x15);
>> +	if (!client)
>> +		return -ENOMEM;
>> +
>> +	do {
>> +		/* Read hello, ignore data, depends on initial power state */
>> +		ret = i2c_master_recv(client, buff, 4);
>> +		if (ret != 4)
>> +			break;
>> +
>> +		/* Request width */
>> +		buff[0] = EKTF2127_REQUEST;
>> +		buff[1] = EKTF2127_WIDTH;
>> +		buff[2] = 0x00;
>> +		buff[3] = 0x00;
>> +		ret = i2c_master_send(client, buff, 4);
>> +		if (ret != 4)
>> +			break;
>> +
>> +		msleep(20);
>> +
>> +		/* Read response */
>> +		ret = i2c_master_recv(client, buff, 4);
>> +		if (ret != 4)
>> +			break;
>> +			
>> +		if (buff[0] == EKTF2127_RESPONSE && buff[1] == EKTF2127_WIDTH) {
>> +			data->touchscreen_addr = 0x15;
>> +			data->touchscreen_compatible = "elan,ektf2127";
>> +			data->touchscreen_model = ektf2127;
>> +			dev_info(data->dev, "Found Elan eKTF2127 touchscreen\n");
>> +			ret = 0;
>> +		}
>> +	} while (0);
>> +	i2c_unregister_device(client);
>> +	if (ret == 0 || ret == -ETIMEDOUT /* Bus stuck bail immediately */)
>> +		return ret;
>> +
>> +	/* Check for Zeitec zet6251 touchsceen at addr 0x76 */
>> +	client = i2c_new_dummy(adap, 0x76);
>> +	if (!client)
>> +		return -ENOMEM;
>> +
>> +	/*
>> +	 * We only do a simple read finger data packet test, because some
>> +	 * versions require firmware to be loaded. If not firmware is loaded
>> +	 * the buffer will be filed with 0xff, so we ignore the contents.
>> +	 */
>> +	ret = i2c_master_recv(client, buff, 24);
>> +	if (ret == 24) {
>> +		data->touchscreen_addr = 0x76;
>> +		data->touchscreen_compatible = "zeitec,zet6251";
>> +		data->touchscreen_model = zet6251;
>> +		dev_info(data->dev, "Found Zeitec zet6251 touchscreen\n");
>> +		ret = 0;
>> +	}
>
> I can understand having a switch here since it’s quite complicated but it would be better to
> have a structure that defines them i.e.
>
> struct touchscreen_detect_data {
> 	u32 chip_id;
> 	int addr;
> 	const char *compatible;
> 	enum touchscreen_model model;
> 	
> };

Having a chip-d in there will only work for the gsl1680,
not for the ektf not for the zeitec. I could use
an array of structs addressed by enum touchscreen_model
holding some of the other data, but that would boil
down to only addr and compatible. and adding that
kinda indirection does not make the code more readable
IMHO.

> static const struct touchscreen_detect_data ts_detect_data[] = {
> 	{
> 		.chip_id = 0xa0820000,
> 		.addr = 0x40,
> 		.compatible = “silead,gsl1680”,
> 		.model = gsl1680_a082,
> 	}, ...
> };
>
> And so on, and restructuring by having different paths by touchscreen model type.
>
>
>> +	i2c_unregister_device(client);
>> +	if (ret == 0 || ret == -ETIMEDOUT /* Bus stuck bail immediately */)
>> +		return ret;
>> +
>> +	return -ENODEV;
>> +}
>> +
>> +static int q8_hardwaremgr_do_probe(struct q8_hardwaremgr_data *data,
>> +				   const char *prefix, probe_func func)
>> +{
>> +	struct device *dev = data->dev;
>> +	struct device_node *np;
>> +	struct i2c_adapter *adap;
>> +	struct regulator *reg;
>> +	struct gpio_desc *gpio;
>> +	int ret = 0;
>> +
>> +	np = of_parse_phandle(dev->of_node, prefix, 0);
>> +	if (!np) {
>> +		dev_err(dev, "Error %s not set\n", prefix);
>> +		return -EINVAL;
>> +	}
>> +
>> +	adap = of_get_i2c_adapter_by_node(np->parent);
>> +	if (!adap) {
>> +		ret = -EPROBE_DEFER;
>> +		goto put_node;
>> +	}
>> +
>> +	reg = regulator_get_optional(dev, prefix);
>> +	if (IS_ERR(reg)) {
>> +		ret = PTR_ERR(reg);
>> +		if (ret == -EPROBE_DEFER)
>> +			goto put_adapter;
>> +		reg = NULL;
>> +	}
>> +
>> +	gpio = fwnode_get_named_gpiod(&np->fwnode, "power-gpios");
>> +	if (IS_ERR(gpio)) {
>> +		ret = PTR_ERR(gpio);
>> +		if (ret == -EPROBE_DEFER)
>> +			goto put_reg;
>> +		gpio = NULL;
>> +	}
>> +
>> +	/* First try with only the power gpio driven high */
>> +	if (gpio) {
>> +		ret = gpiod_direction_output(gpio, 1);
>> +		if (ret)
>> +			goto put_gpio;
>> +	}
>> +
>> +	dev_info(dev, "Looking for %s without a regulator\n", prefix);
>> +	ret = func(data, adap);
>> +	if (ret != 0 && reg) {
>> +		/* Second try, also enable the regulator */
>> +		ret = regulator_enable(reg);
>> +		if (ret)
>> +			goto restore_gpio;
>> +
>> +		dev_info(dev, "Looking for %s with a regulator\n", prefix);
>> +		ret = func(data, adap);
>> +		if (ret == 0)
>> +			data->touchscreen_needs_regulator = true;
>> +
>> +		regulator_disable(reg);
>> +	}
>> +	ret = 0; /* Not finding a device is not an error */
>> +
>> +restore_gpio:
>> +	if (gpio)
>> +		gpiod_direction_output(gpio, 0);
>> +put_gpio:
>> +	if (gpio)
>> +		gpiod_put(gpio);
>> +put_reg:
>> +	if (reg)
>> +		regulator_put(reg);
>> +put_adapter:
>> +	i2c_put_adapter(adap);
>> +
>> +put_node:
>> +	of_node_put(np);
>> +
>> +	return ret;
>> +}
>> +
>> +static void q8_hardwaremgr_apply_gsl1680_a082_variant(
>> +	struct q8_hardwaremgr_data *data)
>> +{
>> +	if (touchscreen_variant != -1) {
>> +		data->touchscreen_variant = touchscreen_variant;
>> +	} else {
>> +		if (of_machine_is_compatible("allwinner,sun8i-a33"))
>> +			data->touchscreen_variant = 1;
>> +		else
>> +			data->touchscreen_variant = 0;
>> +	}
>> +
>> +	switch (data->touchscreen_variant) {
>> +	default:
>> +		dev_warn(data->dev, "Error unknown touchscreen_variant %d using 0\n",
>> +			 touchscreen_variant);
>> +		/* Fall through */
>> +	case 0:
>> +		data->touchscreen_width = 1024;
>> +		data->touchscreen_height = 600;
>> +		data->touchscreen_fw_name = "gsl1680-a082-q8-700.fw";
>> +		break;
>> +	case 1:
>> +		data->touchscreen_width = 480;
>> +		data->touchscreen_height = 800;
>> +		data->touchscreen_swap_x_y = 1;
>> +		data->touchscreen_fw_name = "gsl1680-a082-q8-a70.fw";
>> +		break;
>> +	}
>> +}
>> +
>> +static void q8_hardwaremgr_apply_gsl1680_b482_variant(
>> +	struct q8_hardwaremgr_data *data)
>> +{
>> +	if (touchscreen_variant != -1)
>> +		data->touchscreen_variant = touchscreen_variant;
>> +
>> +	switch (data->touchscreen_variant) {
>> +	default:
>> +		dev_warn(data->dev, "Error unknown touchscreen_variant %d using 0\n",
>> +			 touchscreen_variant);
>> +		/* Fall through */
>> +	case 0:
>> +		data->touchscreen_width = 960;
>> +		data->touchscreen_height = 640;
>> +		data->touchscreen_fw_name = "gsl1680-b482-q8-d702.fw";
>> +		break;
>> +	case 1:
>> +		data->touchscreen_width = 960;
>> +		data->touchscreen_height = 640;
>> +		data->touchscreen_fw_name = "gsl1680-b482-q8-a70.fw";
>> +		break;
>> +	}
>> +}
>> +
>> +static void q8_hardwaremgr_issue_gsl1680_warning(
>> +	struct q8_hardwaremgr_data *data)
>> +{
>> +	dev_warn(data->dev, "gsl1680 touchscreen may require kernel cmdline parameters to function properly\n");
>> +	dev_warn(data->dev, "Try q8_hardwaremgr.touchscreen_invert_x=1 if x coordinates are inverted\n");
>> +	dev_warn(data->dev, "Try q8_hardwaremgr.touchscreen_variant=%d if coordinates are all over the place\n",
>> +		 !data->touchscreen_variant);
>> +
>> +#define	show(x) \
>> +	dev_info(data->dev, #x " %d (%s)\n", data->x, \
>> +		 (x == -1) ? "auto" : "user supplied")
>> +
>> +	show(touchscreen_variant);
>> +	show(touchscreen_width);
>> +	show(touchscreen_height);
>> +	show(touchscreen_invert_x);
>> +	show(touchscreen_invert_y);
>> +	show(touchscreen_swap_x_y);
>> +	dev_info(data->dev, "touchscreen_fw_name %s (%s)\n",
>> +		 data->touchscreen_fw_name,
>> +		 (touchscreen_fw_name == NULL) ? "auto" : "user supplied");
>> +#undef show
>> +}
>> +
>> +static void q8_hardwaremgr_apply_touchscreen(struct q8_hardwaremgr_data *data)
>> +{
>> +	struct device *dev = data->dev;
>> +	struct of_changeset cset;
>> +	struct device_node *np;
>> +
>> +	switch (data->touchscreen_model) {
>> +	case touchscreen_unknown:
>> +		return;
>> +	case gsl1680_a082:
>> +		q8_hardwaremgr_apply_gsl1680_a082_variant(data);
>> +		break;
>> +	case gsl1680_b482:
>> +		q8_hardwaremgr_apply_gsl1680_b482_variant(data);
>> +		break;
>> +	case ektf2127:
>> +	case zet6251:
>> +		/* These have only 1 variant */
>> +		break;
>> +	}
>> +
>> +	if (touchscreen_width != -1)
>> +		data->touchscreen_width = touchscreen_width;
>> +
>> +	if (touchscreen_height != -1)
>> +		data->touchscreen_height = touchscreen_height;
>> +
>> +	if (touchscreen_invert_x != -1)
>> +		data->touchscreen_invert_x = touchscreen_invert_x;
>> +
>> +	if (touchscreen_invert_y != -1)
>> +		data->touchscreen_invert_y = touchscreen_invert_y;
>> +
>> +	if (touchscreen_swap_x_y != -1)
>> +		data->touchscreen_swap_x_y = touchscreen_swap_x_y;
>> +
>> +	if (touchscreen_fw_name)
>> +		data->touchscreen_fw_name = touchscreen_fw_name;
>> +
>> +	if (data->touchscreen_model == gsl1680_a082 ||
>> +	    data->touchscreen_model == gsl1680_b482)
>> +		q8_hardwaremgr_issue_gsl1680_warning(data);
>> +
>> +	np = of_parse_phandle(data->dev->of_node, "touchscreen", 0);
>> +	/* Never happens already checked in q8_hardwaremgr_do_probe() */
>> +	if (WARN_ON(!np))
>> +		return;
>> +
>> +	of_changeset_init(&cset);
>> +	of_changeset_add_property_u32(&cset, np, "reg", data->touchscreen_addr);
>> +	of_changeset_add_property_string(&cset, np, "compatible",
>> +					 data->touchscreen_compatible);
>> +
>> +	if (data->touchscreen_width)
>> +		of_changeset_add_property_u32(&cset, np, "touchscreen-size-x",
>> +					      data->touchscreen_width);
>> +	if (data->touchscreen_height)
>> +		of_changeset_add_property_u32(&cset, np, "touchscreen-size-y",
>> +					      data->touchscreen_height);
>> +	if (data->touchscreen_invert_x)
>> +		of_changeset_add_property_bool(&cset, np,
>> +					       "touchscreen-inverted-x");
>> +	if (data->touchscreen_invert_y)
>> +		of_changeset_add_property_bool(&cset, np,
>> +					       "touchscreen-inverted-y");
>> +	if (data->touchscreen_swap_x_y)
>> +		of_changeset_add_property_bool(&cset, np,
>> +					       "touchscreen-swapped-x-y");
>> +	if (data->touchscreen_fw_name)
>> +		of_changeset_add_property_string(&cset, np, "firmware-name",
>> +						 data->touchscreen_fw_name);
>> +	if (data->touchscreen_needs_regulator) {
>> +		struct property *p;
>> +
>> +		p = of_find_property(dev->of_node, "touchscreen-supply", NULL);
>> +		/* Never happens already checked in q8_hardwaremgr_do_probe() */
>> +		if (WARN_ON(!p))
>> +			return;
>> +
>> +		of_changeset_add_property_copy(&cset, np, "vddio-supply",
>> +					       p->value, p->length);
>> +	}
>> +
>> +	of_changeset_update_property_string(&cset, np, "status", "okay");
>> +	of_changeset_apply(&cset);
>> +
>> +	of_node_put(np);
>> +}
>> +
>> +static int q8_hardwaremgr_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct q8_hardwaremgr_data *data;
>> +	int ret = 0;
>> +
>> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
>> +	if (!data)
>> +		return -ENOMEM;
>> +
>> +	data->dev = &pdev->dev;
>> +
>> +	ret = q8_hardwaremgr_do_probe(data, "touchscreen",
>> +				      q8_hardwaremgr_probe_touchscreen);
>> +	if (ret)
>> +		goto error;
>> +
>> +	/*
>> +	 * Our pinctrl may conflict with the pinctrl of the detected devices
>> +	 * we're adding, so remove it before adding detected devices.
>> +	 */
>> +	if (dev->pins) {
>> +		devm_pinctrl_put(dev->pins->p);
>> +		devm_kfree(dev, dev->pins);
>> +		dev->pins = NULL;
>> +	}
>> +
>
> Hmm, that’s weird for sure. How can it happen?

Nope, not weird. The touchscreen's power-gpios needs to
have the right drive-strength / pull-up setting, both
during q8_hardwaremgr_probe and when the actual driver
is using it. So the dt node for both contains a
phandle to a pinctrl for the power-gpio, as soon as
we start applying the dt changes, the touchscreen's
probe method will get called and just before that
the device-core will try to set the default pinctrl
for the touchscreen dt node/platform dev, which will
fail because the pins in there are owned by the
q8-hardwaremgr dt node/platform dev, which causes
an error in the kernel log (don't remember if it
also caused the touchscreen driver to not load or
not).

Note that with Rob's suggestion to not have
a q8-hardwaremgr node at all (*), the q8-hardwaremgr
code will need to do the pinctrl setting itself
and then it also doing the releasing later on
will feel more natural / will be expected.

Regards,

Hans


*) Assuming I've understood Rob correctly
wrt this.

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Re: [RFC] misc: Add Allwinner Q8 tablet hardware manager

[Rob Herring]

On Thu, Sep 1, 2016 at 2:08 PM, Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets
> of which a new batch is produced every few weeks. Each batch uses a
> different mix of touchscreen, accelerometer and wifi peripherals.
>
> Given that each batch is different creating a devicetree for each variant
> is not desirable. This commit adds a Q8 tablet hardware manager which
> auto-detects the touchscreen and accelerometer so that a single generic
> dts can be used for these tablets.
>
> The wifi is connected to a discoverable bus (sdio or usb) and will be
> autodetected by the mmc resp. usb subsystems.
>
> Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  .../misc/allwinner,sunxi-q8-hardwaremgr.txt        |  52 +++
>  drivers/misc/Kconfig                               |  12 +
>  drivers/misc/Makefile                              |   1 +
>  drivers/misc/q8-hardwaremgr.c                      | 512 +++++++++++++++++++++
>  4 files changed, 577 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
>  create mode 100644 drivers/misc/q8-hardwaremgr.c
>
> diff --git a/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
> new file mode 100644
> index 0000000..f428bf5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
> @@ -0,0 +1,52 @@
> +Q8 tablet hardware manager
> +--------------------------
> +
> +Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets of
> +which a new batch is produced every few weeks. Each batch uses a different
> +mix of touchscreen, accelerometer and wifi peripherals.
> +
> +Given that each batch is different creating a devicetree for each variant is
> +not desirable. The Q8 tablet hardware manager bindings are bindings for an os
> +module which auto-detects the touchscreen so that a single
> +generic dts can be used for these tablets.
> +
> +The wifi is connected to a discoverable bus and will be autodetected by the os.
> +
> +Required properties:
> + - compatible         : "allwinner,sunxi-q8-hardwaremgr"
> + - touchscreen        : phandle of a template touchscreen node, this must be a
> +                       child node of the touchscreen i2c bus
> +
> +Optional properties:
> + - touchscreen-supply : regulator phandle for the touchscreen vdd supply

While I said I think you should be using overlays here, you could also
do it without. However, this node has to go. It is not h/w, and you
are putting it here purely to instantiate a driver. For the
touchscreen property, surely you know where the touchscreen is located
in the DT? If not, of_find_node_by_name()? For touchscreen-supply, I
assume this is to turn on the supply so you can talk to the touch
controller. There's no reason the supply can't just be in the
touchscreen node itself.

> +
> +touschreen node required properties:
> + - interrupt-parent   : phandle pointing to the interrupt controller
> +                       serving the touchscreen interrupt
> + - interrupts         : interrupt specification for the touchscreen interrupt
> + - power-gpios        : Specification for the pin connected to the touchscreen's
> +                       enable / wake pin. This needs to be driven high to
> +                       enable the touchscreen controller
> +
> +Example:
> +
> +/ {
> +       hwmgr {
> +               compatible = "allwinner,sunxi-q8-hardwaremgr";
> +               touchscreen = <&touchscreen>;
> +               touchscreen-supply = <&reg_ldo_io1>;
> +       };
> +};
> +
> +&i2c0 {
> +       touchscreen: touchscreen@0 {
> +               interrupt-parent = <&pio>;
> +               interrupts = <1 5 IRQ_TYPE_EDGE_FALLING>; /* PB5 */
> +               power-gpios = <&pio 7 1 GPIO_ACTIVE_HIGH>; /* PH1 */
> +               /*
> +                * Enabled by sunxi-q8-hardwaremgr if it detects a
> +                * known model touchscreen.
> +                */
> +               status = "disabled";
> +       };
> +};

Re: [linux-sunxi] Re: [RFC] misc: Add Allwinner Q8 tablet hardware manager

[Hans de Goede]

Hi,

On 09-09-16 23:41, Rob Herring wrote:
> On Thu, Sep 1, 2016 at 2:08 PM, Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
>> Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets
>> of which a new batch is produced every few weeks. Each batch uses a
>> different mix of touchscreen, accelerometer and wifi peripherals.
>>
>> Given that each batch is different creating a devicetree for each variant
>> is not desirable. This commit adds a Q8 tablet hardware manager which
>> auto-detects the touchscreen and accelerometer so that a single generic
>> dts can be used for these tablets.
>>
>> The wifi is connected to a discoverable bus (sdio or usb) and will be
>> autodetected by the mmc resp. usb subsystems.
>>
>> Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> ---
>>  .../misc/allwinner,sunxi-q8-hardwaremgr.txt        |  52 +++
>>  drivers/misc/Kconfig                               |  12 +
>>  drivers/misc/Makefile                              |   1 +
>>  drivers/misc/q8-hardwaremgr.c                      | 512 +++++++++++++++++++++
>>  4 files changed, 577 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
>>  create mode 100644 drivers/misc/q8-hardwaremgr.c
>>
>> diff --git a/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
>> new file mode 100644
>> index 0000000..f428bf5
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
>> @@ -0,0 +1,52 @@
>> +Q8 tablet hardware manager
>> +--------------------------
>> +
>> +Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets of
>> +which a new batch is produced every few weeks. Each batch uses a different
>> +mix of touchscreen, accelerometer and wifi peripherals.
>> +
>> +Given that each batch is different creating a devicetree for each variant is
>> +not desirable. The Q8 tablet hardware manager bindings are bindings for an os
>> +module which auto-detects the touchscreen so that a single
>> +generic dts can be used for these tablets.
>> +
>> +The wifi is connected to a discoverable bus and will be autodetected by the os.
>> +
>> +Required properties:
>> + - compatible         : "allwinner,sunxi-q8-hardwaremgr"
>> + - touchscreen        : phandle of a template touchscreen node, this must be a
>> +                       child node of the touchscreen i2c bus
>> +
>> +Optional properties:
>> + - touchscreen-supply : regulator phandle for the touchscreen vdd supply
>
> While I said I think you should be using overlays here, you could also
> do it without.

Good, because I believe that doing things without overlays will
be much easier. If you look at the actual implementation you will
see that it sets a lot of properties (touchscreen width, height,
inversion, axis-swapping, firmware-name) based on various sources,
the explosion of possible overlays from this is huge, and if
we're going to runtime patch the overlays then why use them at all
and not just runtime generate all the info ?

> However, this node has to go. It is not h/w, and you
> are putting it here purely to instantiate a driver.

With "this" in "this node has to go", do you mean the node
with the "allwinner,sunxi-q8-hardwaremgr" compatible, or
do you mean the touchscreen template node ?

> For the
> touchscreen property, surely you know where the touchscreen is located
> in the DT?

Nope q8 tablets come with A13, A23 or A33 SoCs, A23/A33 are pin
compatible with each other, but the A13 is not, this leads to
the touchscreen being on a different i2c bus, so I cannot hardcode
things, likewise the power-gpios and interrupt found in the
touchscreen node differ between the A13 vs A23/A33.

I actually had a touchscreen-i2c-bus property containing a
phandle to the i2c controller for the bus which has the
touchscreen in an earlier revision + touchscreen-gpios
and touchscreen-supply properties, I can switch to that
if you prefer that over having a touchscreen template node.

 > If not, of_find_node_by_name()?

Still a bit confused about what you do not like,
(touchscreen template node vs q8-hardwaremgr node).

I guess (based on context) you do not want the
q8-hardwaremgr node ?

So the q8-hardwaremgr code should activate based on
the machine compatible I presume? How does that
work with module autoloading ?

If you do not want the q8-hardwaremgr node and thus
no touchscreen property them yes I can use
of_find_node_by_name(), but I thought that was
generally frowned up on?

> For touchscreen-supply, I
> assume this is to turn on the supply so you can talk to the touch
> controller. There's no reason the supply can't just be in the
> touchscreen node itself.

Only a few q8 tablets actually use the regulator, so
the hardwaremgr first tries detecting the touchscreen
without it, and only if it does not find anything then
tries with it, and adds a property to the touchscreen
node for it, but I guess I can do this other way
around and have it be present in the (incomplete /
template) touchscreen node and delete it from it if
not necessary.

That + using of_find_node_by_name() should indeed allow
me to remove the q8-hardwaremgr node. Assuming there is
an answer to the module auto loading, as I expect most
distros to build this as a module.

Regards,

Hans





>
>> +
>> +touschreen node required properties:
>> + - interrupt-parent   : phandle pointing to the interrupt controller
>> +                       serving the touchscreen interrupt
>> + - interrupts         : interrupt specification for the touchscreen interrupt
>> + - power-gpios        : Specification for the pin connected to the touchscreen's
>> +                       enable / wake pin. This needs to be driven high to
>> +                       enable the touchscreen controller
>> +
>> +Example:
>> +
>> +/ {
>> +       hwmgr {
>> +               compatible = "allwinner,sunxi-q8-hardwaremgr";
>> +               touchscreen = <&touchscreen>;
>> +               touchscreen-supply = <&reg_ldo_io1>;
>> +       };
>> +};
>> +
>> +&i2c0 {
>> +       touchscreen: touchscreen@0 {
>> +               interrupt-parent = <&pio>;
>> +               interrupts = <1 5 IRQ_TYPE_EDGE_FALLING>; /* PB5 */
>> +               power-gpios = <&pio 7 1 GPIO_ACTIVE_HIGH>; /* PH1 */
>> +               /*
>> +                * Enabled by sunxi-q8-hardwaremgr if it detects a
>> +                * known model touchscreen.
>> +                */
>> +               status = "disabled";
>> +       };
>> +};
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Re: Re: [RFC] misc: Add Allwinner Q8 tablet hardware manager

[Rob Herring]

On Sat, Sep 10, 2016 at 08:12:32PM +0200, Hans de Goede wrote:
> Hi,
> 
> On 09-09-16 23:41, Rob Herring wrote:
> >On Thu, Sep 1, 2016 at 2:08 PM, Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> >>Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets
> >>of which a new batch is produced every few weeks. Each batch uses a
> >>different mix of touchscreen, accelerometer and wifi peripherals.
> >>
> >>Given that each batch is different creating a devicetree for each variant
> >>is not desirable. This commit adds a Q8 tablet hardware manager which
> >>auto-detects the touchscreen and accelerometer so that a single generic
> >>dts can be used for these tablets.
> >>
> >>The wifi is connected to a discoverable bus (sdio or usb) and will be
> >>autodetected by the mmc resp. usb subsystems.
> >>
> >>Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> >>---
> >> .../misc/allwinner,sunxi-q8-hardwaremgr.txt        |  52 +++
> >> drivers/misc/Kconfig                               |  12 +
> >> drivers/misc/Makefile                              |   1 +
> >> drivers/misc/q8-hardwaremgr.c                      | 512 +++++++++++++++++++++
> >> 4 files changed, 577 insertions(+)
> >> create mode 100644 Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
> >> create mode 100644 drivers/misc/q8-hardwaremgr.c
> >>
> >>diff --git a/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
> >>new file mode 100644
> >>index 0000000..f428bf5
> >>--- /dev/null
> >>+++ b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt
> >>@@ -0,0 +1,52 @@
> >>+Q8 tablet hardware manager
> >>+--------------------------
> >>+
> >>+Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets of
> >>+which a new batch is produced every few weeks. Each batch uses a different
> >>+mix of touchscreen, accelerometer and wifi peripherals.
> >>+
> >>+Given that each batch is different creating a devicetree for each variant is
> >>+not desirable. The Q8 tablet hardware manager bindings are bindings for an os
> >>+module which auto-detects the touchscreen so that a single
> >>+generic dts can be used for these tablets.
> >>+
> >>+The wifi is connected to a discoverable bus and will be autodetected by the os.
> >>+
> >>+Required properties:
> >>+ - compatible         : "allwinner,sunxi-q8-hardwaremgr"
> >>+ - touchscreen        : phandle of a template touchscreen node, this must be a
> >>+                       child node of the touchscreen i2c bus
> >>+
> >>+Optional properties:
> >>+ - touchscreen-supply : regulator phandle for the touchscreen vdd supply
> >
> >While I said I think you should be using overlays here, you could also
> >do it without.
> 
> Good, because I believe that doing things without overlays will
> be much easier. If you look at the actual implementation you will
> see that it sets a lot of properties (touchscreen width, height,
> inversion, axis-swapping, firmware-name) based on various sources,
> the explosion of possible overlays from this is huge, and if
> we're going to runtime patch the overlays then why use them at all
> and not just runtime generate all the info ?

That's fine if run-time makes more sense. I'd just like to move in the 
direction of applying a hunk of changes rather than C code creating 
nodes and properties one-by-one.
 
> >However, this node has to go. It is not h/w, and you
> >are putting it here purely to instantiate a driver.
> 
> With "this" in "this node has to go", do you mean the node
> with the "allwinner,sunxi-q8-hardwaremgr" compatible, or
> do you mean the touchscreen template node ?

Given that this binding section above is concerning 
allwinner,sunxi-q8-hardwaremgr, that is what I'm referring to.

> 
> >For the
> >touchscreen property, surely you know where the touchscreen is located
> >in the DT?
> 
> Nope q8 tablets come with A13, A23 or A33 SoCs, A23/A33 are pin
> compatible with each other, but the A13 is not, this leads to
> the touchscreen being on a different i2c bus, so I cannot hardcode
> things, likewise the power-gpios and interrupt found in the
> touchscreen node differ between the A13 vs A23/A33.

Either the touchscreen node name is "touchscreen" or you can have 
compatible string for q8-touchscreen and use of_find_node_by_name or 
of_find_compatible_node. Doesn't matter what bus it is on. It only 
requires that there is only 1 node.

> I actually had a touchscreen-i2c-bus property containing a
> phandle to the i2c controller for the bus which has the
> touchscreen in an earlier revision + touchscreen-gpios
> and touchscreen-supply properties, I can switch to that
> if you prefer that over having a touchscreen template node.
> 
> > If not, of_find_node_by_name()?
> 
> Still a bit confused about what you do not like,
> (touchscreen template node vs q8-hardwaremgr node).
> 
> I guess (based on context) you do not want the
> q8-hardwaremgr node ?
> 
> So the q8-hardwaremgr code should activate based on
> the machine compatible I presume? 

Either that, or if you have the board specific compatible in the 
touchscreen node, then you could have a driver for it. That driver would 
need to probe the device and then create the "real" device.
 
> How does that
> work with module autoloading ?

Can't non-DT based platform drivers do autoloading? Regardless, not 
really my problem from a binding perspective.

> If you do not want the q8-hardwaremgr node and thus
> no touchscreen property them yes I can use
> of_find_node_by_name(), but I thought that was
> generally frowned up on?

Generally we do prefer finding things by compatible strings. But there 
are exceptions and doing fix-ups like this is a good example.

> >For touchscreen-supply, I
> >assume this is to turn on the supply so you can talk to the touch
> >controller. There's no reason the supply can't just be in the
> >touchscreen node itself.
> 
> Only a few q8 tablets actually use the regulator, so
> the hardwaremgr first tries detecting the touchscreen
> without it, and only if it does not find anything then
> tries with it, and adds a property to the touchscreen
> node for it, but I guess I can do this other way
> around and have it be present in the (incomplete /
> template) touchscreen node and delete it from it if
> not necessary.

Right.

Rob

Re: [RFC 0/1] misc: Add Allwinner Q8 tablet hardware manager

[Rob Herring]

On Thu, Sep 1, 2016 at 2:08 PM, Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> Hi All,
>
> Here is a first RFC for the q8 tablet hw-manager I've been talking
> about for a while now.
>
> The touchscreen part is finished, I'll start working on the
> accelerometer bits next.

This at least partially overlaps with the "overlay manager" just
posted. A dev board having different devices attached and a production
device have 2nd source components are not really different problems.
We need a common solution and can't have each platform making up their
own scheme. What's different for you is how you select what changes or
overlay to apply and that is fine to be platform specific. I think you
should be using overlays here as well.

> Note that this requires the "of: changesets: Introduce changeset
> helper methods" patch from Pantelis. If that is still not upstream
> when I'm ready to post a non RFC, I'll post a new version of that
> myself.

I'm waiting for it to be reposted. IIRC, I only had some minor comments.

Rob

Re: [RFC 0/1] misc: Add Allwinner Q8 tablet hardware manager

[Mark Rutland]

Hi,

On Fri, Sep 09, 2016 at 04:32:06PM -0500, Rob Herring wrote:
> On Thu, Sep 1, 2016 at 2:08 PM, Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> > Hi All,
> >
> > Here is a first RFC for the q8 tablet hw-manager I've been talking
> > about for a while now.
> >
> > The touchscreen part is finished, I'll start working on the
> > accelerometer bits next.
> 
> This at least partially overlaps with the "overlay manager" just
> posted. A dev board having different devices attached and a production
> device have 2nd source components are not really different problems.
> We need a common solution and can't have each platform making up their
> own scheme.

To follow up discussions at ELC-E, I agree that we need a common solution (if
this has to happen in the kernel rather than in an earlier stage of the boot
process).

Otherwise, we're creating pseudo-board-files, and a whole new set of problems
for ourselves.

Thanks
Mark.