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7ca6740cd1
The ADC driver always programs all possible ADC values and discards them except for the value IIO asked for. On the am335x-evm the driver programs four values and it takes 500us to gather them. Reducing the number of conversations down to the (required) one also reduces the busy loop down to 125us. This leads to another error, namely the FIFOCOUNT register is sometimes (like one out of 10 attempts) not updated in time leading to EBUSY. The next read has the FIFOCOUNT register updated. Checking for the ADCSTAT register for being idle isn't a good choice either. The problem is that if TSC is used at the same time, the HW completes the conversation for ADC *and* before the driver noticed it, the HW begins to perform a TSC conversation and so the driver never seen the HW idle. The next time we would have two values in the FIFO but since the driver reads everything we always see the current one. So instead of polling for the IDLE bit in ADCStatus register, we should check the FIFOCOUNT register. It should be one instead of zero because we request one value. This change in turn leads to another error. Sometimes if TSC & ADC are used together the TSC starts generating interrupts even if nobody actually touched the touchscreen. The interrupts seem valid because TSC's FIFO is filled with values for each channel of the TSC. This condition stops after a few ADC reads but will occur again. Not good. On top of this (even without the changes I just mentioned) there is a ADC & TSC lockup condition which was reported to me by Jeff Lance including the following test case: A busy loop of "cat /sys/bus/iio/devices/iio\:device0/in_voltage4_raw" and a mug on touch screen. With this setup, the hardware will lockup after something between 20 minutes and it could take up to a couple of hours. During that lockup, the ADCSTAT register says 0x30 (or 0x70) which means STEP_ID = IDLE and FSM_BUSY = yes. That means the hardware says that it is idle and busy at the same time which is an invalid condition. For all this reasons I decided to rework this TSC/ADC part and add a handshake / synchronization here: First the ADC signals that it needs the HW and writes a 0 mask into the SE register. The HW (if active) will complete the current conversation and become idle. The TSC driver will gather the values from the FIFO (woken up by an interrupt) and won't "enable" another conversation. Instead it will wake up the ADC driver which is already waiting. The ADC driver will start "its" conversation and once it is done, it will enable the TSC steps so the TSC will work again. After this rework I haven't observed the lockup so far. Plus the busy loop has been reduced from 500us to 125us. The continues-read mode remains unchanged. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
188 lines
5.4 KiB
C
188 lines
5.4 KiB
C
#ifndef __LINUX_TI_AM335X_TSCADC_MFD_H
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#define __LINUX_TI_AM335X_TSCADC_MFD_H
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/*
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* TI Touch Screen / ADC MFD driver
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*
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* Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation version 2.
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*
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* This program is distributed "as is" WITHOUT ANY WARRANTY of any
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* kind, whether express or implied; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/mfd/core.h>
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#define REG_RAWIRQSTATUS 0x024
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#define REG_IRQSTATUS 0x028
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#define REG_IRQENABLE 0x02C
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#define REG_IRQCLR 0x030
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#define REG_IRQWAKEUP 0x034
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#define REG_CTRL 0x040
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#define REG_ADCFSM 0x044
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#define REG_CLKDIV 0x04C
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#define REG_SE 0x054
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#define REG_IDLECONFIG 0x058
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#define REG_CHARGECONFIG 0x05C
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#define REG_CHARGEDELAY 0x060
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#define REG_STEPCONFIG(n) (0x64 + ((n) * 8))
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#define REG_STEPDELAY(n) (0x68 + ((n) * 8))
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#define REG_FIFO0CNT 0xE4
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#define REG_FIFO0THR 0xE8
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#define REG_FIFO1CNT 0xF0
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#define REG_FIFO1THR 0xF4
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#define REG_FIFO0 0x100
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#define REG_FIFO1 0x200
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/* Register Bitfields */
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/* IRQ wakeup enable */
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#define IRQWKUP_ENB BIT(0)
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/* Step Enable */
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#define STEPENB_MASK (0x1FFFF << 0)
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#define STEPENB(val) ((val) << 0)
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#define ENB(val) (1 << (val))
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#define STPENB_STEPENB STEPENB(0x1FFFF)
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#define STPENB_STEPENB_TC STEPENB(0x1FFF)
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/* IRQ enable */
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#define IRQENB_HW_PEN BIT(0)
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#define IRQENB_FIFO0THRES BIT(2)
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#define IRQENB_FIFO0OVRRUN BIT(3)
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#define IRQENB_FIFO0UNDRFLW BIT(4)
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#define IRQENB_FIFO1THRES BIT(5)
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#define IRQENB_FIFO1OVRRUN BIT(6)
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#define IRQENB_FIFO1UNDRFLW BIT(7)
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#define IRQENB_PENUP BIT(9)
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/* Step Configuration */
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#define STEPCONFIG_MODE_MASK (3 << 0)
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#define STEPCONFIG_MODE(val) ((val) << 0)
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#define STEPCONFIG_MODE_SWCNT STEPCONFIG_MODE(1)
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#define STEPCONFIG_MODE_HWSYNC STEPCONFIG_MODE(2)
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#define STEPCONFIG_AVG_MASK (7 << 2)
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#define STEPCONFIG_AVG(val) ((val) << 2)
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#define STEPCONFIG_AVG_16 STEPCONFIG_AVG(4)
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#define STEPCONFIG_XPP BIT(5)
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#define STEPCONFIG_XNN BIT(6)
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#define STEPCONFIG_YPP BIT(7)
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#define STEPCONFIG_YNN BIT(8)
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#define STEPCONFIG_XNP BIT(9)
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#define STEPCONFIG_YPN BIT(10)
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#define STEPCONFIG_INM_MASK (0xF << 15)
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#define STEPCONFIG_INM(val) ((val) << 15)
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#define STEPCONFIG_INM_ADCREFM STEPCONFIG_INM(8)
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#define STEPCONFIG_INP_MASK (0xF << 19)
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#define STEPCONFIG_INP(val) ((val) << 19)
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#define STEPCONFIG_INP_AN4 STEPCONFIG_INP(4)
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#define STEPCONFIG_INP_ADCREFM STEPCONFIG_INP(8)
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#define STEPCONFIG_FIFO1 BIT(26)
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/* Delay register */
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#define STEPDELAY_OPEN_MASK (0x3FFFF << 0)
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#define STEPDELAY_OPEN(val) ((val) << 0)
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#define STEPCONFIG_OPENDLY STEPDELAY_OPEN(0x098)
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#define STEPDELAY_SAMPLE_MASK (0xFF << 24)
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#define STEPDELAY_SAMPLE(val) ((val) << 24)
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#define STEPCONFIG_SAMPLEDLY STEPDELAY_SAMPLE(0)
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/* Charge Config */
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#define STEPCHARGE_RFP_MASK (7 << 12)
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#define STEPCHARGE_RFP(val) ((val) << 12)
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#define STEPCHARGE_RFP_XPUL STEPCHARGE_RFP(1)
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#define STEPCHARGE_INM_MASK (0xF << 15)
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#define STEPCHARGE_INM(val) ((val) << 15)
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#define STEPCHARGE_INM_AN1 STEPCHARGE_INM(1)
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#define STEPCHARGE_INP_MASK (0xF << 19)
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#define STEPCHARGE_INP(val) ((val) << 19)
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#define STEPCHARGE_RFM_MASK (3 << 23)
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#define STEPCHARGE_RFM(val) ((val) << 23)
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#define STEPCHARGE_RFM_XNUR STEPCHARGE_RFM(1)
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/* Charge delay */
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#define CHARGEDLY_OPEN_MASK (0x3FFFF << 0)
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#define CHARGEDLY_OPEN(val) ((val) << 0)
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#define CHARGEDLY_OPENDLY CHARGEDLY_OPEN(1)
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/* Control register */
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#define CNTRLREG_TSCSSENB BIT(0)
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#define CNTRLREG_STEPID BIT(1)
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#define CNTRLREG_STEPCONFIGWRT BIT(2)
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#define CNTRLREG_POWERDOWN BIT(4)
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#define CNTRLREG_AFE_CTRL_MASK (3 << 5)
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#define CNTRLREG_AFE_CTRL(val) ((val) << 5)
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#define CNTRLREG_4WIRE CNTRLREG_AFE_CTRL(1)
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#define CNTRLREG_5WIRE CNTRLREG_AFE_CTRL(2)
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#define CNTRLREG_8WIRE CNTRLREG_AFE_CTRL(3)
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#define CNTRLREG_TSCENB BIT(7)
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/* FIFO READ Register */
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#define FIFOREAD_DATA_MASK (0xfff << 0)
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#define FIFOREAD_CHNLID_MASK (0xf << 16)
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/* Sequencer Status */
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#define SEQ_STATUS BIT(5)
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#define ADC_CLK 3000000
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#define TOTAL_STEPS 16
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#define TOTAL_CHANNELS 8
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#define FIFO1_THRESHOLD 19
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/*
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* time in us for processing a single channel, calculated as follows:
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*
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* num cycles = open delay + (sample delay + conv time) * averaging
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*
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* num cycles: 152 + (1 + 13) * 16 = 376
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*
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* clock frequency: 26MHz / 8 = 3.25MHz
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* clock period: 1 / 3.25MHz = 308ns
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*
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* processing time: 376 * 308ns = 116us
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*/
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#define IDLE_TIMEOUT 116 /* microsec */
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#define TSCADC_CELLS 2
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struct ti_tscadc_dev {
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struct device *dev;
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struct regmap *regmap_tscadc;
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void __iomem *tscadc_base;
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int irq;
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int used_cells; /* 1-2 */
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int tsc_cell; /* -1 if not used */
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int adc_cell; /* -1 if not used */
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struct mfd_cell cells[TSCADC_CELLS];
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u32 reg_se_cache;
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bool adc_waiting;
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bool adc_in_use;
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wait_queue_head_t reg_se_wait;
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spinlock_t reg_lock;
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unsigned int clk_div;
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/* tsc device */
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struct titsc *tsc;
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/* adc device */
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struct adc_device *adc;
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};
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static inline struct ti_tscadc_dev *ti_tscadc_dev_get(struct platform_device *p)
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{
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struct ti_tscadc_dev **tscadc_dev = p->dev.platform_data;
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return *tscadc_dev;
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}
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void am335x_tsc_se_set_cache(struct ti_tscadc_dev *tsadc, u32 val);
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void am335x_tsc_se_set_once(struct ti_tscadc_dev *tsadc, u32 val);
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void am335x_tsc_se_clr(struct ti_tscadc_dev *tsadc, u32 val);
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void am335x_tsc_se_adc_done(struct ti_tscadc_dev *tsadc);
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#endif
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