linux-stable/include/linux/mfd/ti_am335x_tscadc.h
Vignesh R 4b3ab9372f iio: adc: ti_am335x_tscadc: Improve accuracy of measurement
When performing single ended measurements with TSCADC, its recommended
to set negative input (SEL_INM_SWC_3_0) of ADC step to ADC's VREFN in the
corresponding STEP_CONFIGx register.

Also, the positive(SEL_RFP_SWC_2_0) and negative(SEL_RFM_SWC_1_0)
reference voltage for ADC step needs to be set to VREFP and VREFN
respectively in STEP_CONFIGx register.
Without these changes, there may be variation of as much as ~2% in the
ADC's digital output which is bad for precise measurement.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-12-03 11:33:20 +00:00

202 lines
5.9 KiB
C

#ifndef __LINUX_TI_AM335X_TSCADC_MFD_H
#define __LINUX_TI_AM335X_TSCADC_MFD_H
/*
* TI Touch Screen / ADC MFD driver
*
* Copyright (C) 2012 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/mfd/core.h>
#define REG_RAWIRQSTATUS 0x024
#define REG_IRQSTATUS 0x028
#define REG_IRQENABLE 0x02C
#define REG_IRQCLR 0x030
#define REG_IRQWAKEUP 0x034
#define REG_DMAENABLE_SET 0x038
#define REG_DMAENABLE_CLEAR 0x03c
#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) * 8))
#define REG_STEPDELAY(n) (0x68 + ((n) * 8))
#define REG_FIFO0CNT 0xE4
#define REG_FIFO0THR 0xE8
#define REG_FIFO1CNT 0xF0
#define REG_FIFO1THR 0xF4
#define REG_DMA1REQ 0xF8
#define REG_FIFO0 0x100
#define REG_FIFO1 0x200
/* Register Bitfields */
/* IRQ wakeup enable */
#define IRQWKUP_ENB BIT(0)
/* Step Enable */
#define STEPENB_MASK (0x1FFFF << 0)
#define STEPENB(val) ((val) << 0)
#define ENB(val) (1 << (val))
#define STPENB_STEPENB STEPENB(0x1FFFF)
#define STPENB_STEPENB_TC STEPENB(0x1FFF)
/* IRQ enable */
#define IRQENB_HW_PEN BIT(0)
#define IRQENB_EOS BIT(1)
#define IRQENB_FIFO0THRES BIT(2)
#define IRQENB_FIFO0OVRRUN BIT(3)
#define IRQENB_FIFO0UNDRFLW BIT(4)
#define IRQENB_FIFO1THRES BIT(5)
#define IRQENB_FIFO1OVRRUN BIT(6)
#define IRQENB_FIFO1UNDRFLW BIT(7)
#define IRQENB_PENUP BIT(9)
/* Step Configuration */
#define STEPCONFIG_MODE_MASK (3 << 0)
#define STEPCONFIG_MODE(val) ((val) << 0)
#define STEPCONFIG_MODE_SWCNT STEPCONFIG_MODE(1)
#define STEPCONFIG_MODE_HWSYNC STEPCONFIG_MODE(2)
#define STEPCONFIG_AVG_MASK (7 << 2)
#define STEPCONFIG_AVG(val) ((val) << 2)
#define STEPCONFIG_AVG_16 STEPCONFIG_AVG(4)
#define STEPCONFIG_XPP BIT(5)
#define STEPCONFIG_XNN BIT(6)
#define STEPCONFIG_YPP BIT(7)
#define STEPCONFIG_YNN BIT(8)
#define STEPCONFIG_XNP BIT(9)
#define STEPCONFIG_YPN BIT(10)
#define STEPCONFIG_RFP(val) ((val) << 12)
#define STEPCONFIG_RFP_VREFP (0x3 << 12)
#define STEPCONFIG_INM_MASK (0xF << 15)
#define STEPCONFIG_INM(val) ((val) << 15)
#define STEPCONFIG_INM_ADCREFM STEPCONFIG_INM(8)
#define STEPCONFIG_INP_MASK (0xF << 19)
#define STEPCONFIG_INP(val) ((val) << 19)
#define STEPCONFIG_INP_AN4 STEPCONFIG_INP(4)
#define STEPCONFIG_INP_ADCREFM STEPCONFIG_INP(8)
#define STEPCONFIG_FIFO1 BIT(26)
#define STEPCONFIG_RFM(val) ((val) << 23)
#define STEPCONFIG_RFM_VREFN (0x3 << 23)
/* Delay register */
#define STEPDELAY_OPEN_MASK (0x3FFFF << 0)
#define STEPDELAY_OPEN(val) ((val) << 0)
#define STEPCONFIG_OPENDLY STEPDELAY_OPEN(0x098)
#define STEPDELAY_SAMPLE_MASK (0xFF << 24)
#define STEPDELAY_SAMPLE(val) ((val) << 24)
#define STEPCONFIG_SAMPLEDLY STEPDELAY_SAMPLE(0)
/* Charge Config */
#define STEPCHARGE_RFP_MASK (7 << 12)
#define STEPCHARGE_RFP(val) ((val) << 12)
#define STEPCHARGE_RFP_XPUL STEPCHARGE_RFP(1)
#define STEPCHARGE_INM_MASK (0xF << 15)
#define STEPCHARGE_INM(val) ((val) << 15)
#define STEPCHARGE_INM_AN1 STEPCHARGE_INM(1)
#define STEPCHARGE_INP_MASK (0xF << 19)
#define STEPCHARGE_INP(val) ((val) << 19)
#define STEPCHARGE_RFM_MASK (3 << 23)
#define STEPCHARGE_RFM(val) ((val) << 23)
#define STEPCHARGE_RFM_XNUR STEPCHARGE_RFM(1)
/* Charge delay */
#define CHARGEDLY_OPEN_MASK (0x3FFFF << 0)
#define CHARGEDLY_OPEN(val) ((val) << 0)
#define CHARGEDLY_OPENDLY CHARGEDLY_OPEN(0x400)
/* Control register */
#define CNTRLREG_TSCSSENB BIT(0)
#define CNTRLREG_STEPID BIT(1)
#define CNTRLREG_STEPCONFIGWRT BIT(2)
#define CNTRLREG_POWERDOWN BIT(4)
#define CNTRLREG_AFE_CTRL_MASK (3 << 5)
#define CNTRLREG_AFE_CTRL(val) ((val) << 5)
#define CNTRLREG_4WIRE CNTRLREG_AFE_CTRL(1)
#define CNTRLREG_5WIRE CNTRLREG_AFE_CTRL(2)
#define CNTRLREG_8WIRE CNTRLREG_AFE_CTRL(3)
#define CNTRLREG_TSCENB BIT(7)
/* FIFO READ Register */
#define FIFOREAD_DATA_MASK (0xfff << 0)
#define FIFOREAD_CHNLID_MASK (0xf << 16)
/* DMA ENABLE/CLEAR Register */
#define DMA_FIFO0 BIT(0)
#define DMA_FIFO1 BIT(1)
/* Sequencer Status */
#define SEQ_STATUS BIT(5)
#define CHARGE_STEP 0x11
#define ADC_CLK 3000000
#define TOTAL_STEPS 16
#define TOTAL_CHANNELS 8
#define FIFO1_THRESHOLD 19
/*
* time in us for processing a single channel, calculated as follows:
*
* max num cycles = open delay + (sample delay + conv time) * averaging
*
* max num cycles: 262143 + (255 + 13) * 16 = 266431
*
* clock frequency: 26MHz / 8 = 3.25MHz
* clock period: 1 / 3.25MHz = 308ns
*
* max processing time: 266431 * 308ns = 83ms(approx)
*/
#define IDLE_TIMEOUT 83 /* milliseconds */
#define TSCADC_CELLS 2
struct ti_tscadc_dev {
struct device *dev;
struct regmap *regmap;
void __iomem *tscadc_base;
phys_addr_t tscadc_phys_base;
int irq;
int used_cells; /* 1-2 */
int tsc_wires;
int tsc_cell; /* -1 if not used */
int adc_cell; /* -1 if not used */
struct mfd_cell cells[TSCADC_CELLS];
u32 reg_se_cache;
bool adc_waiting;
bool adc_in_use;
wait_queue_head_t reg_se_wait;
spinlock_t reg_lock;
unsigned int clk_div;
/* tsc device */
struct titsc *tsc;
/* adc device */
struct adc_device *adc;
};
static inline struct ti_tscadc_dev *ti_tscadc_dev_get(struct platform_device *p)
{
struct ti_tscadc_dev **tscadc_dev = p->dev.platform_data;
return *tscadc_dev;
}
void am335x_tsc_se_set_cache(struct ti_tscadc_dev *tsadc, u32 val);
void am335x_tsc_se_set_once(struct ti_tscadc_dev *tsadc, u32 val);
void am335x_tsc_se_clr(struct ti_tscadc_dev *tsadc, u32 val);
void am335x_tsc_se_adc_done(struct ti_tscadc_dev *tsadc);
#endif