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linux/drivers/input/touchscreen/ti_tscadc.c
Rachna Patil 1b8be32e69 Input: add support for TI Touchscreen controller 
This patch adds support for TI's touchscreen
controller for a 4/5/8 wire resistive panel
that is directly fed to the ADC.

This touchscreen controller will be part of
AM335x TI SoC. The TRM can be found at:
http://www.ti.com/lit/ug/spruh73a/spruh73a.pdf

Signed-off-by: Patil, Rachna <rachna@ti.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2012-03-04 08:45:00 -08:00

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/*
* TI Touch Screen driver
*
* Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com/
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation version 2.
*
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
* kind, whether express or implied; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/input/ti_tscadc.h>
#include <linux/delay.h>
#define REG_IRQEOI 0x020
#define REG_RAWIRQSTATUS 0x024
#define REG_IRQSTATUS 0x028
#define REG_IRQENABLE 0x02C
#define REG_IRQWAKEUP 0x034
#define REG_CTRL 0x040
#define REG_ADCFSM 0x044
#define REG_CLKDIV 0x04C
#define REG_SE 0x054
#define REG_IDLECONFIG 0x058
#define REG_CHARGECONFIG 0x05C
#define REG_CHARGEDELAY 0x060
#define REG_STEPCONFIG(n) (0x64 + ((n - 1) * 8))
#define REG_STEPDELAY(n) (0x68 + ((n - 1) * 8))
#define REG_STEPCONFIG13 0x0C4
#define REG_STEPDELAY13 0x0C8
#define REG_STEPCONFIG14 0x0CC
#define REG_STEPDELAY14 0x0D0
#define REG_FIFO0CNT 0xE4
#define REG_FIFO1THR 0xF4
#define REG_FIFO0 0x100
#define REG_FIFO1 0x200
/* Register Bitfields */
#define IRQWKUP_ENB BIT(0)
#define STPENB_STEPENB 0x7FFF
#define IRQENB_FIFO1THRES BIT(5)
#define IRQENB_PENUP BIT(9)
#define STEPCONFIG_MODE_HWSYNC 0x2
#define STEPCONFIG_SAMPLES_AVG (1 << 4)
#define STEPCONFIG_XPP (1 << 5)
#define STEPCONFIG_XNN (1 << 6)
#define STEPCONFIG_YPP (1 << 7)
#define STEPCONFIG_YNN (1 << 8)
#define STEPCONFIG_XNP (1 << 9)
#define STEPCONFIG_YPN (1 << 10)
#define STEPCONFIG_INM (1 << 18)
#define STEPCONFIG_INP (1 << 20)
#define STEPCONFIG_INP_5 (1 << 21)
#define STEPCONFIG_FIFO1 (1 << 26)
#define STEPCONFIG_OPENDLY 0xff
#define STEPCONFIG_Z1 (3 << 19)
#define STEPIDLE_INP (1 << 22)
#define STEPCHARGE_RFP (1 << 12)
#define STEPCHARGE_INM (1 << 15)
#define STEPCHARGE_INP (1 << 19)
#define STEPCHARGE_RFM (1 << 23)
#define STEPCHARGE_DELAY 0x1
#define CNTRLREG_TSCSSENB (1 << 0)
#define CNTRLREG_STEPID (1 << 1)
#define CNTRLREG_STEPCONFIGWRT (1 << 2)
#define CNTRLREG_4WIRE (1 << 5)
#define CNTRLREG_5WIRE (1 << 6)
#define CNTRLREG_8WIRE (3 << 5)
#define CNTRLREG_TSCENB (1 << 7)
#define ADCFSM_STEPID 0x10
#define SEQ_SETTLE 275
#define ADC_CLK 3000000
#define MAX_12BIT ((1 << 12) - 1)
#define TSCADC_DELTA_X 15
#define TSCADC_DELTA_Y 15
struct tscadc {
struct input_dev *input;
struct clk *tsc_ick;
void __iomem *tsc_base;
unsigned int irq;
unsigned int wires;
unsigned int x_plate_resistance;
bool pen_down;
};
static unsigned int tscadc_readl(struct tscadc *ts, unsigned int reg)
{
return readl(ts->tsc_base + reg);
}
static void tscadc_writel(struct tscadc *tsc, unsigned int reg,
unsigned int val)
{
writel(val, tsc->tsc_base + reg);
}
static void tscadc_step_config(struct tscadc *ts_dev)
{
unsigned int config;
int i;
/* Configure the Step registers */
config = STEPCONFIG_MODE_HWSYNC |
STEPCONFIG_SAMPLES_AVG | STEPCONFIG_XPP;
switch (ts_dev->wires) {
case 4:
config |= STEPCONFIG_INP | STEPCONFIG_XNN;
break;
case 5:
config |= STEPCONFIG_YNN |
STEPCONFIG_INP_5 | STEPCONFIG_XNN |
STEPCONFIG_YPP;
break;
case 8:
config |= STEPCONFIG_INP | STEPCONFIG_XNN;
break;
}
for (i = 1; i < 7; i++) {
tscadc_writel(ts_dev, REG_STEPCONFIG(i), config);
tscadc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY);
}
config = 0;
config = STEPCONFIG_MODE_HWSYNC |
STEPCONFIG_SAMPLES_AVG | STEPCONFIG_YNN |
STEPCONFIG_INM | STEPCONFIG_FIFO1;
switch (ts_dev->wires) {
case 4:
config |= STEPCONFIG_YPP;
break;
case 5:
config |= STEPCONFIG_XPP | STEPCONFIG_INP_5 |
STEPCONFIG_XNP | STEPCONFIG_YPN;
break;
case 8:
config |= STEPCONFIG_YPP;
break;
}
for (i = 7; i < 13; i++) {
tscadc_writel(ts_dev, REG_STEPCONFIG(i), config);
tscadc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY);
}
config = 0;
/* Charge step configuration */
config = STEPCONFIG_XPP | STEPCONFIG_YNN |
STEPCHARGE_RFP | STEPCHARGE_RFM |
STEPCHARGE_INM | STEPCHARGE_INP;
tscadc_writel(ts_dev, REG_CHARGECONFIG, config);
tscadc_writel(ts_dev, REG_CHARGEDELAY, STEPCHARGE_DELAY);
config = 0;
/* Configure to calculate pressure */
config = STEPCONFIG_MODE_HWSYNC |
STEPCONFIG_SAMPLES_AVG | STEPCONFIG_YPP |
STEPCONFIG_XNN | STEPCONFIG_INM;
tscadc_writel(ts_dev, REG_STEPCONFIG13, config);
tscadc_writel(ts_dev, REG_STEPDELAY13, STEPCONFIG_OPENDLY);
config |= STEPCONFIG_Z1 | STEPCONFIG_FIFO1;
tscadc_writel(ts_dev, REG_STEPCONFIG14, config);
tscadc_writel(ts_dev, REG_STEPDELAY14, STEPCONFIG_OPENDLY);
tscadc_writel(ts_dev, REG_SE, STPENB_STEPENB);
}
static void tscadc_idle_config(struct tscadc *ts_config)
{
unsigned int idleconfig;
idleconfig = STEPCONFIG_YNN |
STEPCONFIG_INM |
STEPCONFIG_YPN | STEPIDLE_INP;
tscadc_writel(ts_config, REG_IDLECONFIG, idleconfig);
}
static void tscadc_read_coordinates(struct tscadc *ts_dev,
unsigned int *x, unsigned int *y)
{
unsigned int fifocount = tscadc_readl(ts_dev, REG_FIFO0CNT);
unsigned int prev_val_x = ~0, prev_val_y = ~0;
unsigned int prev_diff_x = ~0, prev_diff_y = ~0;
unsigned int read, diff;
unsigned int i;
/*
* Delta filter is used to remove large variations in sampled
* values from ADC. The filter tries to predict where the next
* coordinate could be. This is done by taking a previous
* coordinate and subtracting it form current one. Further the
* algorithm compares the difference with that of a present value,
* if true the value is reported to the sub system.
*/
for (i = 0; i < fifocount - 1; i++) {
read = tscadc_readl(ts_dev, REG_FIFO0) & 0xfff;
diff = abs(read - prev_val_x);
if (diff < prev_diff_x) {
prev_diff_x = diff;
*x = read;
}
prev_val_x = read;
read = tscadc_readl(ts_dev, REG_FIFO1) & 0xfff;
diff = abs(read - prev_val_y);
if (diff < prev_diff_y) {
prev_diff_y = diff;
*y = read;
}
prev_val_y = read;
}
}
static irqreturn_t tscadc_irq(int irq, void *dev)
{
struct tscadc *ts_dev = dev;
struct input_dev *input_dev = ts_dev->input;
unsigned int status, irqclr = 0;
unsigned int x = 0, y = 0;
unsigned int z1, z2, z;
unsigned int fsm;
status = tscadc_readl(ts_dev, REG_IRQSTATUS);
if (status & IRQENB_FIFO1THRES) {
tscadc_read_coordinates(ts_dev, &x, &y);
z1 = tscadc_readl(ts_dev, REG_FIFO0) & 0xfff;
z2 = tscadc_readl(ts_dev, REG_FIFO1) & 0xfff;
if (ts_dev->pen_down && z1 != 0 && z2 != 0) {
/*
* Calculate pressure using formula
* Resistance(touch) = x plate resistance *
* x postion/4096 * ((z2 / z1) - 1)
*/
z = z2 - z1;
z *= x;
z *= ts_dev->x_plate_resistance;
z /= z1;
z = (z + 2047) >> 12;
if (z <= MAX_12BIT) {
input_report_abs(input_dev, ABS_X, x);
input_report_abs(input_dev, ABS_Y, y);
input_report_abs(input_dev, ABS_PRESSURE, z);
input_report_key(input_dev, BTN_TOUCH, 1);
input_sync(input_dev);
}
}
irqclr |= IRQENB_FIFO1THRES;
}
/*
* Time for sequencer to settle, to read
* correct state of the sequencer.
*/
udelay(SEQ_SETTLE);
status = tscadc_readl(ts_dev, REG_RAWIRQSTATUS);
if (status & IRQENB_PENUP) {
/* Pen up event */
fsm = tscadc_readl(ts_dev, REG_ADCFSM);
if (fsm == ADCFSM_STEPID) {
ts_dev->pen_down = false;
input_report_key(input_dev, BTN_TOUCH, 0);
input_report_abs(input_dev, ABS_PRESSURE, 0);
input_sync(input_dev);
} else {
ts_dev->pen_down = true;
}
irqclr |= IRQENB_PENUP;
}
tscadc_writel(ts_dev, REG_IRQSTATUS, irqclr);
/* check pending interrupts */
tscadc_writel(ts_dev, REG_IRQEOI, 0x0);
tscadc_writel(ts_dev, REG_SE, STPENB_STEPENB);
return IRQ_HANDLED;
}
/*
* The functions for inserting/removing driver as a module.
*/
static int __devinit tscadc_probe(struct platform_device *pdev)
{
const struct tsc_data *pdata = pdev->dev.platform_data;
struct resource *res;
struct tscadc *ts_dev;
struct input_dev *input_dev;
struct clk *clk;
int err;
int clk_value, ctrl, irq;
if (!pdata) {
dev_err(&pdev->dev, "missing platform data.\n");
return -EINVAL;
}
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(&pdev->dev, "no memory resource defined.\n");
return -EINVAL;
}
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(&pdev->dev, "no irq ID is specified.\n");
return -EINVAL;
}
/* Allocate memory for device */
ts_dev = kzalloc(sizeof(struct tscadc), GFP_KERNEL);
input_dev = input_allocate_device();
if (!ts_dev || !input_dev) {
dev_err(&pdev->dev, "failed to allocate memory.\n");
err = -ENOMEM;
goto err_free_mem;
}
ts_dev->input = input_dev;
ts_dev->irq = irq;
ts_dev->wires = pdata->wires;
ts_dev->x_plate_resistance = pdata->x_plate_resistance;
res = request_mem_region(res->start, resource_size(res), pdev->name);
if (!res) {
dev_err(&pdev->dev, "failed to reserve registers.\n");
err = -EBUSY;
goto err_free_mem;
}
ts_dev->tsc_base = ioremap(res->start, resource_size(res));
if (!ts_dev->tsc_base) {
dev_err(&pdev->dev, "failed to map registers.\n");
err = -ENOMEM;
goto err_release_mem_region;
}
err = request_irq(ts_dev->irq, tscadc_irq,
0, pdev->dev.driver->name, ts_dev);
if (err) {
dev_err(&pdev->dev, "failed to allocate irq.\n");
goto err_unmap_regs;
}
ts_dev->tsc_ick = clk_get(&pdev->dev, "adc_tsc_ick");
if (IS_ERR(ts_dev->tsc_ick)) {
dev_err(&pdev->dev, "failed to get TSC ick\n");
goto err_free_irq;
}
clk_enable(ts_dev->tsc_ick);
clk = clk_get(&pdev->dev, "adc_tsc_fck");
if (IS_ERR(clk)) {
dev_err(&pdev->dev, "failed to get TSC fck\n");
err = PTR_ERR(clk);
goto err_disable_clk;
}
clk_value = clk_get_rate(clk) / ADC_CLK;
clk_put(clk);
if (clk_value < 7) {
dev_err(&pdev->dev, "clock input less than min clock requirement\n");
goto err_disable_clk;
}
/* CLKDIV needs to be configured to the value minus 1 */
tscadc_writel(ts_dev, REG_CLKDIV, clk_value - 1);
/* Enable wake-up of the SoC using touchscreen */
tscadc_writel(ts_dev, REG_IRQWAKEUP, IRQWKUP_ENB);
ctrl = CNTRLREG_STEPCONFIGWRT |
CNTRLREG_TSCENB |
CNTRLREG_STEPID;
switch (ts_dev->wires) {
case 4:
ctrl |= CNTRLREG_4WIRE;
break;
case 5:
ctrl |= CNTRLREG_5WIRE;
break;
case 8:
ctrl |= CNTRLREG_8WIRE;
break;
}
tscadc_writel(ts_dev, REG_CTRL, ctrl);
tscadc_idle_config(ts_dev);
tscadc_writel(ts_dev, REG_IRQENABLE, IRQENB_FIFO1THRES);
tscadc_step_config(ts_dev);
tscadc_writel(ts_dev, REG_FIFO1THR, 6);
ctrl |= CNTRLREG_TSCSSENB;
tscadc_writel(ts_dev, REG_CTRL, ctrl);
input_dev->name = "ti-tsc-adc";
input_dev->dev.parent = &pdev->dev;
input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, 0, 0);
input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);
/* register to the input system */
err = input_register_device(input_dev);
if (err)
goto err_disable_clk;
platform_set_drvdata(pdev, ts_dev);
return 0;
err_disable_clk:
clk_disable(ts_dev->tsc_ick);
clk_put(ts_dev->tsc_ick);
err_free_irq:
free_irq(ts_dev->irq, ts_dev);
err_unmap_regs:
iounmap(ts_dev->tsc_base);
err_release_mem_region:
release_mem_region(res->start, resource_size(res));
err_free_mem:
input_free_device(input_dev);
kfree(ts_dev);
return err;
}
static int __devexit tscadc_remove(struct platform_device *pdev)
{
struct tscadc *ts_dev = platform_get_drvdata(pdev);
struct resource *res;
free_irq(ts_dev->irq, ts_dev);
input_unregister_device(ts_dev->input);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
iounmap(ts_dev->tsc_base);
release_mem_region(res->start, resource_size(res));
clk_disable(ts_dev->tsc_ick);
clk_put(ts_dev->tsc_ick);
kfree(ts_dev);
platform_set_drvdata(pdev, NULL);
return 0;
}
static struct platform_driver ti_tsc_driver = {
.probe = tscadc_probe,
.remove = __devexit_p(tscadc_remove),
.driver = {
.name = "tsc",
.owner = THIS_MODULE,
},
};
module_platform_driver(ti_tsc_driver);
MODULE_DESCRIPTION("TI touchscreen controller driver");
MODULE_AUTHOR("Rachna Patil <rachna@ti.com>");
MODULE_LICENSE("GPL");
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