linux_dsm_epyc7002/include/linux/i2c/sx150x.h
Gregory Bean 5affb60772 gpio: sx150x: correct and refine reset-on-probe behavior
Replace the arbitrary software-reset call from the device-probe
method, because:

- It is defective.  To work correctly, it should be two byte writes,
  not a single word write.  As it stands, it does nothing.

- Some devices with sx150x expanders installed have their NRESET pins
  ganged on the same line, so resetting one causes the others to reset -
  not a nice thing to do arbitrarily!

- The probe, usually taking place at boot, implies a recent hard-reset,
  so a software reset at this point is just a waste of energy anyway.

Therefore, make it optional, defaulting to off, as this will match the
common case of probing at powerup and also matches the current broken
no-op behavior.

Signed-off-by: Gregory Bean <gbean@codeaurora.org>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-09-09 18:57:24 -07:00

83 lines
4.1 KiB
C

/*
* Driver for the Semtech SX150x I2C GPIO Expanders
*
* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#ifndef __LINUX_I2C_SX150X_H
#define __LINUX_I2C_SX150X_H
/**
* struct sx150x_platform_data - config data for SX150x driver
* @gpio_base: The index number of the first GPIO assigned to this
* GPIO expander. The expander will create a block of
* consecutively numbered gpios beginning at the given base,
* with the size of the block depending on the model of the
* expander chip.
* @oscio_is_gpo: If set to true, the driver will configure OSCIO as a GPO
* instead of as an oscillator, increasing the size of the
* GP(I)O pool created by this expander by one. The
* output-only GPO pin will be added at the end of the block.
* @io_pullup_ena: A bit-mask which enables or disables the pull-up resistor
* for each IO line in the expander. Setting the bit at
* position n will enable the pull-up for the IO at
* the corresponding offset. For chips with fewer than
* 16 IO pins, high-end bits are ignored.
* @io_pulldn_ena: A bit-mask which enables-or disables the pull-down
* resistor for each IO line in the expander. Setting the
* bit at position n will enable the pull-down for the IO at
* the corresponding offset. For chips with fewer than
* 16 IO pins, high-end bits are ignored.
* @io_open_drain_ena: A bit-mask which enables-or disables open-drain
* operation for each IO line in the expander. Setting the
* bit at position n enables open-drain operation for
* the IO at the corresponding offset. Clearing the bit
* enables regular push-pull operation for that IO.
* For chips with fewer than 16 IO pins, high-end bits
* are ignored.
* @io_polarity: A bit-mask which enables polarity inversion for each IO line
* in the expander. Setting the bit at position n inverts
* the polarity of that IO line, while clearing it results
* in normal polarity. For chips with fewer than 16 IO pins,
* high-end bits are ignored.
* @irq_summary: The 'summary IRQ' line to which the GPIO expander's INT line
* is connected, via which it reports interrupt events
* across all GPIO lines. This must be a real,
* pre-existing IRQ line.
* Setting this value < 0 disables the irq_chip functionality
* of the driver.
* @irq_base: The first 'virtual IRQ' line at which our block of GPIO-based
* IRQ lines will appear. Similarly to gpio_base, the expander
* will create a block of irqs beginning at this number.
* This value is ignored if irq_summary is < 0.
* @reset_during_probe: If set to true, the driver will trigger a full
* reset of the chip at the beginning of the probe
* in order to place it in a known state.
*/
struct sx150x_platform_data {
unsigned gpio_base;
bool oscio_is_gpo;
u16 io_pullup_ena;
u16 io_pulldn_ena;
u16 io_open_drain_ena;
u16 io_polarity;
int irq_summary;
unsigned irq_base;
bool reset_during_probe;
};
#endif /* __LINUX_I2C_SX150X_H */