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ARM: pxa: magician: Add support for ADS7846 touchscreen
This patch adds a support for ADS7846 touchscreen driver. The basic functionality was tested, x_plate_ohms and y_plate_ohms were physically measured. The value pressure_max was empirically set to match the measured range, which is affected by x_plate_ohms and ADS samples. The value of keep_vref_on should be set. A tested model (T-Mobile MDA Compact PM10A) doesn't seem to use Vref pin as the input from an external source. On this model the unset keep_vref_on cause high jitter of measured values. SPI framing pin (gpio_cs) must be used in GPIO mode due to an incompatible autoframing of PXA27x controller and ADS7846 device. Signed-off-by: Petr Cvek <petr.cvek@tul.cz> Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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2ea659a9ef
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2 changed files with 84 additions and 1 deletions
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@ -24,6 +24,7 @@
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#define GPIO10_MAGICIAN_GSM_IRQ 10
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#define GPIO11_MAGICIAN_GSM_OUT1 11
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#define GPIO13_MAGICIAN_CPLD_IRQ 13
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#define GPIO14_MAGICIAN_TSC2046_CS 14
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#define GPIO18_MAGICIAN_UNKNOWN 18
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#define GPIO22_MAGICIAN_VIBRA_EN 22
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#define GPIO26_MAGICIAN_GSM_POWER 26
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@ -54,6 +54,10 @@
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#include "devices.h"
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#include "generic.h"
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#include <linux/spi/spi.h>
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#include <linux/spi/pxa2xx_spi.h>
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#include <linux/spi/ads7846.h>
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static unsigned long magician_pin_config[] __initdata = {
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/* SDRAM and Static Memory I/O Signals */
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@ -85,7 +89,7 @@ static unsigned long magician_pin_config[] __initdata = {
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/* SSP 2 TSC2046 touchscreen */
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GPIO19_SSP2_SCLK,
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GPIO14_SSP2_SFRM,
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MFP_CFG_OUT(GPIO14, AF0, DRIVE_HIGH), /* frame as GPIO */
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GPIO89_SSP2_TXD,
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GPIO88_SSP2_RXD,
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@ -674,6 +678,37 @@ static struct platform_device bq24022 = {
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},
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};
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/*
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* fixed regulator for ads7846
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*/
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static struct regulator_consumer_supply ads7846_supply =
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REGULATOR_SUPPLY("vcc", "spi2.0");
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static struct regulator_init_data vads7846_regulator = {
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.constraints = {
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.valid_ops_mask = REGULATOR_CHANGE_STATUS,
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},
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.num_consumer_supplies = 1,
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.consumer_supplies = &ads7846_supply,
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};
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static struct fixed_voltage_config vads7846 = {
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.supply_name = "vads7846",
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.microvolts = 3300000, /* probably */
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.gpio = -EINVAL,
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.startup_delay = 0,
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.init_data = &vads7846_regulator,
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};
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static struct platform_device vads7846_device = {
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.name = "reg-fixed-voltage",
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.id = -1,
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.dev = {
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.platform_data = &vads7846,
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},
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};
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/*
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* Vcore regulator MAX1587A
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*/
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@ -851,6 +886,49 @@ static struct i2c_pxa_platform_data magician_i2c_power_info = {
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.fast_mode = 1,
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};
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/*
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* Touchscreen
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*/
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static struct ads7846_platform_data ads7846_pdata = {
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.model = 7846,
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.x_plate_ohms = 317,
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.y_plate_ohms = 500,
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.pressure_max = 1023, /* with x plate ohms it will overflow 255 */
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.debounce_max = 3, /* first readout is always bad */
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.debounce_tol = 30,
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.debounce_rep = 0,
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.gpio_pendown = GPIO115_MAGICIAN_nPEN_IRQ,
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.keep_vref_on = 1,
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.wakeup = true,
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.vref_delay_usecs = 100,
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.penirq_recheck_delay_usecs = 100,
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};
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struct pxa2xx_spi_chip tsc2046_chip_info = {
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.tx_threshold = 1,
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.rx_threshold = 2,
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.timeout = 64,
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/* NOTICE must be GPIO, incompatibility with hw PXA SPI framing */
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.gpio_cs = GPIO14_MAGICIAN_TSC2046_CS,
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};
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static struct pxa2xx_spi_master magician_spi_info = {
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.num_chipselect = 1,
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.enable_dma = 1,
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};
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static struct spi_board_info ads7846_spi_board_info[] __initdata = {
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{
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.modalias = "ads7846",
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.bus_num = 2,
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.max_speed_hz = 2500000,
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.platform_data = &ads7846_pdata,
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.controller_data = &tsc2046_chip_info,
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.irq = PXA_GPIO_TO_IRQ(GPIO115_MAGICIAN_nPEN_IRQ),
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},
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};
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/*
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* Platform devices
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*/
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@ -865,6 +943,7 @@ static struct platform_device *devices[] __initdata = {
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&power_supply,
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&strataflash,
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&leds_gpio,
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&vads7846_device,
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};
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static struct gpio magician_global_gpios[] = {
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@ -922,6 +1001,9 @@ static void __init magician_init(void)
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} else
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pr_err("LCD detection: CPLD mapping failed\n");
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pxa2xx_set_spi_info(2, &magician_spi_info);
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spi_register_board_info(ARRAY_AND_SIZE(ads7846_spi_board_info));
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regulator_register_always_on(0, "power", pwm_backlight_supply,
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ARRAY_SIZE(pwm_backlight_supply), 5000000);
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