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From: Jean Delvare on 7 Jul 2010 07:40
Hi Trilok, Gregory,

On Wed, 07 Jul 2010 13:53:48 +0530, Trilok Soni wrote:
> On 7/7/2010 4:07 AM, Gregory Bean wrote:
> > Add support for Semtech SX150-series I2C GPIO expanders.
> > Compatible models include:
> >
> > 8 bits: sx1508q
> > 16 bits: sx1509q
> >
> > Signed-off-by: Gregory Bean <gbean(a)codeaurora.org>
>
> Added linux-i2c and Jean Delvare for i2c bits, so not deleting any lines from the code.
>

See my random comments inline below.

> > diff --git a/drivers/gpio/sx150x.c b/drivers/gpio/sx150x.c
> > new file mode 100644
> > index 0000000..0594150
> > --- /dev/null
> > +++ b/drivers/gpio/sx150x.c
> > @@ -0,0 +1,720 @@
> > +/* 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.
> > + */
> > +#include <linux/gpio.h>
> > +#include <linux/i2c.h>
> > +#include <linux/init.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/irq.h>
> > +#include <linux/module.h>
> > +#include <linux/slab.h>
> > +#include <linux/workqueue.h>
> > +#include <linux/i2c/sx150x.h>
> > +
> > +struct sx150x_device_data {
> > + u8 reg_pullup;
> > + u8 reg_pulldn;
> > + u8 reg_drain;
> > + u8 reg_polarity;
> > + u8 reg_dir;
> > + u8 reg_data;
> > + u8 reg_irq_mask;
> > + u8 reg_irq_src;
> > + u8 reg_sense;
> > + u8 reg_clock;
> > + u8 reg_misc;
> > + u8 reg_reset;
> > + u8 ngpios;
> > +};
> > +
> > +/*
> > + * irq_cmds:
> > + *
> > + * A bitmap containing all the commands issued by the interrupt system
> > + * for processing by the work-queue once out of interrupt context.
> > + * A nice, static bitmap avoids the risk of dynamic memory allocation
> > + * and the bitmap is small enough that the wasted space of a worst-case
> > + * allocation is minimal.
> > + * Bits for each gpio are as follows:
> > + *
> > + * 0 - mask
> > + * 1 - unmask
> > + * 2 - sense rising edge
> > + * 3 - sense falling edge
> > + *
> > + * Every group of four bits is for a unique gpio, so bits 0-3 are for IO
> > + * pin 0, 4-7, for pin 1, &c.
> > + */
> > +enum {
> > + CMD_MASK = 0,
> > + CMD_UNMASK = 1,
> > + CMD_RISING = 2,
> > + CMD_FALLING = 3,
> > + CMDS_PER_IO = 4,
> > +};
> > +
> > +#define NCMDBITS (16 * CMDS_PER_IO)
> > +
> > +static inline unsigned cmd_bit(unsigned pin, unsigned cmd)
> > +{
> > + return pin * CMDS_PER_IO + cmd;
> > +}
> > +
> > +struct sx150x_chip {
> > + struct gpio_chip gpio_chip;
> > + struct i2c_client *client;
> > + const struct sx150x_device_data *dev_cfg;
> > + struct mutex mutex;

You must include <linux/mutex.h> then.

> > + int irq_summary;
> > + int irq_base;
> > + u32 irq_sense;
> > + struct irq_chip irq_chip;
> > + struct work_struct irq_mask_ws;
> > + struct work_struct irq_unmask_ws;
> > + struct work_struct irq_set_type_ws;
> > + DECLARE_BITMAP(irq_cmds, NCMDBITS);
> > +};
> > +
> > +static const struct sx150x_device_data sx150x_devices[] = {
> > + [0] = { /* sx1508q */
> > + .reg_pullup = 0x03,
> > + .reg_pulldn = 0x04,
> > + .reg_drain = 0x05,
> > + .reg_polarity = 0x06,
> > + .reg_dir = 0x07,
> > + .reg_data = 0x08,
> > + .reg_irq_mask = 0x09,
> > + .reg_irq_src = 0x0c,
> > + .reg_sense = 0x0b,
> > + .reg_clock = 0x0f,
> > + .reg_misc = 0x10,
> > + .reg_reset = 0x7d,
> > + .ngpios = 8
> > + },
> > + [1] = { /* sx1509q */
> > + .reg_pullup = 0x07,
> > + .reg_pulldn = 0x09,
> > + .reg_drain = 0x0b,
> > + .reg_polarity = 0x0d,
> > + .reg_dir = 0x0f,
> > + .reg_data = 0x11,
> > + .reg_irq_mask = 0x13,
> > + .reg_irq_src = 0x19,
> > + .reg_sense = 0x17,
> > + .reg_clock = 0x1e,
> > + .reg_misc = 0x1f,
> > + .reg_reset = 0x7d,
> > + .ngpios = 16
> > + },
> > +};
> > +
> > +static const struct i2c_device_id sx150x_id[] = {
> > + {"sx1508q", 0},
> > + {"sx1509q", 1},
> > + {}
> > +};
> > +MODULE_DEVICE_TABLE(i2c, sx150x_id);
> > +
> > +static s32 sx150x_i2c_write(struct i2c_client *client, u8 reg, u8 val)
> > +{
> > + s32 err = i2c_smbus_write_byte_data(client, reg, val);
> > +
> > + if (err < 0)
> > + dev_warn(&client->dev,
> > + "i2c write fail: can't write %02x to %02x: %d\n",
> > + val, reg, err);
> > + return err;
> > +}
> > +
> > +static s32 sx150x_i2c_read(struct i2c_client *client, u8 reg, u8 *val)
> > +{
> > + s32 err = i2c_smbus_read_byte_data(client, reg);
> > +
> > + if (err >= 0)
> > + *val = err;
> > + else
> > + dev_warn(&client->dev,
> > + "i2c read fail: can't read from %02x: %d\n",
> > + reg, err);
> > + return err;
> > +}
> > +
> > +static inline bool offset_is_oscio(struct sx150x_chip *chip, unsigned offset)
> > +{
> > + return (chip->dev_cfg->ngpios == offset);
> > +}
> > +
> > +/*
> > + * These utility functions solve the common problem of locating and setting
> > + * configuration bits. Configuration bits are grouped into registers
> > + * whose indexes increase downwards. For example, with eight-bit registers,
> > + * sixteen gpios would have their config bits grouped in the following order:
> > + * REGISTER N-1 [ f e d c b a 9 8 ]
> > + * N [ 7 6 5 4 3 2 1 0 ]
> > + *
> > + * For multi-bit configurations, the pattern gets wider:
> > + * REGISTER N-3 [ f f e e d d c c ]
> > + * N-2 [ b b a a 9 9 8 8 ]
> > + * N-1 [ 7 7 6 6 5 5 4 4 ]
> > + * N [ 3 3 2 2 1 1 0 0 ]
> > + *
> > + * Given the address of the starting register 'N', the index of the gpio
> > + * whose configuration we seek to change, and the width in bits of that
> > + * configuration, these functions allow us to locate the correct
> > + * register and mask the correct bits.
> > + */
> > +static inline void sx150x_find_cfg(u8 offset, u8 width,
> > + u8 *reg, u8 *mask, u8 *shift)
> > +{
> > + *reg -= offset * width / 8;
> > + *mask = (1 << width) - 1;
> > + *shift = (offset * width) % 8;
> > + *mask <<= *shift;
> > +}
> > +
> > +static s32 sx150x_write_cfg(struct sx150x_chip *chip,
> > + u8 offset, u8 width, u8 reg, u8 val)
> > +{
> > + u8 mask;
> > + u8 data;
> > + u8 shift;
> > + s32 err;
> > +
> > + sx150x_find_cfg(offset, width, &reg, &mask, &shift);
> > + err = sx150x_i2c_read(chip->client, reg, &data);
> > + if (err < 0)
> > + return err;
> > +
> > + data &= ~mask;
> > + data |= (val << shift) & mask;
> > + return sx150x_i2c_write(chip->client, reg, data);
> > +}
> > +
> > +static int sx150x_get_io(struct sx150x_chip *chip, unsigned offset)
> > +{
> > + u8 reg = chip->dev_cfg->reg_data;
> > + u8 mask;
> > + u8 data;
> > + u8 shift;
> > + s32 err;
> > +
> > + sx150x_find_cfg(offset, 1, &reg, &mask, &shift);
> > + mutex_lock(&chip->mutex);
> > + err = sx150x_i2c_read(chip->client, reg, &data);
> > + mutex_unlock(&chip->mutex);
> > + if (err >= 0)
> > + err = (data & mask) != 0 ? 1 : 0;
> > +
> > + return err;
> > +}
> > +
> > +static void sx150x_set_oscio(struct sx150x_chip *chip, int val)
> > +{
> > + mutex_lock(&chip->mutex);
> > + sx150x_i2c_write(chip->client,
> > + chip->dev_cfg->reg_clock,
> > + (val ? 0x1f : 0x10));
> > + mutex_unlock(&chip->mutex);
> > +}
> > +
> > +static void sx150x_set_io(struct sx150x_chip *chip, unsigned offset, int val)
> > +{
> > + mutex_lock(&chip->mutex);
> > + sx150x_write_cfg(chip,
> > + offset,
> > + 1,
> > + chip->dev_cfg->reg_data,
> > + (val ? 1 : 0));
> > + mutex_unlock(&chip->mutex);
> > +}
> > +
> > +static int sx150x_io_input(struct sx150x_chip *chip, unsigned offset)
> > +{
> > + int err;
> > +
> > + mutex_lock(&chip->mutex);
> > + err = sx150x_write_cfg(chip,
> > + offset,
> > + 1,
> > + chip->dev_cfg->reg_dir,
> > + 1);
> > + mutex_unlock(&chip->mutex);
> > + return err;
> > +}
> > +
> > +static int sx150x_io_output(struct sx150x_chip *chip, unsigned offset, int val)
> > +{
> > + int err;
> > +
> > + mutex_lock(&chip->mutex);
> > + err = sx150x_write_cfg(chip,
> > + offset,
> > + 1,
> > + chip->dev_cfg->reg_data,
> > + (val ? 1 : 0));
> > + if (err >= 0)
> > + err = sx150x_write_cfg(chip,
> > + offset,
> > + 1,
> > + chip->dev_cfg->reg_dir,
> > + 0);
> > + mutex_unlock(&chip->mutex);
> > + return err;
> > +}
> > +
> > +static int sx150x_gpio_get(struct gpio_chip *gc, unsigned offset)
> > +{
> > + struct sx150x_chip *chip;
> > +
> > + chip = container_of(gc, struct sx150x_chip, gpio_chip);
> > +
> > + if (offset_is_oscio(chip, offset))
> > + return -ENOTSUPP;
> > + else
> > + return sx150x_get_io(chip, offset);
> > +}
> > +
> > +static void sx150x_gpio_set(struct gpio_chip *gc, unsigned offset, int val)
> > +{
> > + struct sx150x_chip *chip;
> > +
> > + chip = container_of(gc, struct sx150x_chip, gpio_chip);
> > +
> > + if (offset_is_oscio(chip, offset))
> > + sx150x_set_oscio(chip, val);
> > + else
> > + sx150x_set_io(chip, offset, val);
> > +}
> > +
> > +static int sx150x_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
> > +{
> > + struct sx150x_chip *chip;
> > +
> > + chip = container_of(gc, struct sx150x_chip, gpio_chip);
> > +
> > + if (offset_is_oscio(chip, offset))
> > + return -ENOTSUPP;
> > + else
> > + return sx150x_io_input(chip, offset);
> > +}
> > +
> > +static int sx150x_gpio_direction_output(struct gpio_chip *gc,
> > + unsigned offset,
> > + int val)
> > +{
> > + struct sx150x_chip *chip;
> > +
> > + chip = container_of(gc, struct sx150x_chip, gpio_chip);
> > +
> > + if (offset_is_oscio(chip, offset))
> > + return 0;
> > + else
> > + return sx150x_io_output(chip, offset, val);
> > +}
> > +
> > +static int sx150x_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
> > +{
> > + struct sx150x_chip *chip;
> > +
> > + chip = container_of(gc, struct sx150x_chip, gpio_chip);
> > +
> > + if (offset >= chip->dev_cfg->ngpios)
> > + return -EINVAL;
> > +
> > + if (chip->irq_base < 0)
> > + return -ENOTSUPP;
> > +
> > + return chip->irq_base + offset;
> > +}
> > +
> > +static void sx150x_irq_mask(unsigned int irq)
> > +{
> > + struct irq_chip *ic;
> > + struct sx150x_chip *chip;
> > +
> > + ic = get_irq_chip(irq);
> > + chip = container_of(ic, struct sx150x_chip, irq_chip);
> > +
> > + set_bit(cmd_bit(irq - chip->irq_base, CMD_MASK), chip->irq_cmds);
> > + schedule_work(&chip->irq_mask_ws);
> > +}
> > +
> > +static void sx150x_irq_mask_wfn(struct work_struct *work)
> > +{
> > + struct sx150x_chip *chip;
> > + unsigned n;
> > +
> > + chip = container_of(work, struct sx150x_chip, irq_mask_ws);
> > +
> > + mutex_lock(&chip->mutex);
> > + for (n = 0; n < chip->dev_cfg->ngpios; ++n) {
> > + if (test_and_clear_bit(cmd_bit(n, CMD_MASK),
> > + chip->irq_cmds)) {
> > + sx150x_write_cfg(chip, n, 1,
> > + chip->dev_cfg->reg_irq_mask, 1);
> > + sx150x_write_cfg(chip, n, 2,
> > + chip->dev_cfg->reg_sense,
> > + 0);
> > + }
> > + }
> > + mutex_unlock(&chip->mutex);
> > +}
>
> Please explain why we are using workqueues for mask/unmasks hooks and irq thread context won't work?
>
> > +
> > +static void sx150x_irq_unmask(unsigned int irq)
> > +{
> > + struct irq_chip *ic;
> > + struct sx150x_chip *chip;
> > +
> > + ic = get_irq_chip(irq);
> > + chip = container_of(ic, struct sx150x_chip, irq_chip);
> > +
> > + set_bit(cmd_bit(irq - chip->irq_base, CMD_UNMASK), chip->irq_cmds);
> > + schedule_work(&chip->irq_unmask_ws);
> > +}
> > +
> > +static void sx150x_irq_unmask_wfn(struct work_struct *work)
> > +{
> > + struct sx150x_chip *chip;
> > + unsigned n;
> > +
> > + chip = container_of(work, struct sx150x_chip, irq_unmask_ws);
> > +
> > + mutex_lock(&chip->mutex);
> > + for (n = 0; n < chip->dev_cfg->ngpios; ++n) {
> > + if (test_and_clear_bit(cmd_bit(n, CMD_UNMASK),
> > + chip->irq_cmds)) {
> > + sx150x_write_cfg(chip, n, 1,
> > + chip->dev_cfg->reg_irq_mask, 0);
> > + sx150x_write_cfg(chip, n, 2,
> > + chip->dev_cfg->reg_sense,
> > + chip->irq_sense >> (n * 2));
> > + }
> > + }
> > + mutex_unlock(&chip->mutex);
> > +}
> > +
> > +static int sx150x_irq_set_type(unsigned int irq, unsigned int flow_type)
> > +{
> > + struct irq_chip *ic;
> > + struct sx150x_chip *chip;
> > + unsigned offset;
> > +
> > + if (flow_type & (IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_LEVEL_LOW))
> > + return -EINVAL;
> > +
> > + ic = get_irq_chip(irq);
> > + chip = container_of(ic, struct sx150x_chip, irq_chip);
> > + offset = irq - chip->irq_base;
> > +
> > + if (flow_type & IRQ_TYPE_EDGE_RISING)
> > + set_bit(cmd_bit(offset, CMD_RISING), chip->irq_cmds);
> > + if (flow_type & IRQ_TYPE_EDGE_FALLING)
> > + set_bit(cmd_bit(offset, CMD_FALLING), chip->irq_cmds);
> > + schedule_work(&chip->irq_set_type_ws);
> > +
> > + return 0;
> > +}
> > +
> > +static void sx150x_irq_set_type_wfn(struct work_struct *work)
> > +{
> > + struct sx150x_chip *chip;
> > + unsigned n;
> > + unsigned val;
> > + int irq;
> > +
> > + chip = container_of(work, struct sx150x_chip, irq_set_type_ws);
> > +
> > + mutex_lock(&chip->mutex);
> > + for (n = 0; n < chip->dev_cfg->ngpios; ++n) {
> > + val = 0;
> > + if (test_and_clear_bit(cmd_bit(n, CMD_RISING),
> > + chip->irq_cmds))
> > + val |= 0x1;
> > + if (test_and_clear_bit(cmd_bit(n, CMD_FALLING),
> > + chip->irq_cmds))
> > + val |= 0x2;
> > +
> > + chip->irq_sense &= ~(3UL << (n * 2));
> > + chip->irq_sense |= val << (n * 2);
> > +
> > + irq = chip->irq_base + n;
> > + if (!(irq_to_desc(irq)->status & IRQ_MASKED))
> > + sx150x_write_cfg(chip, n, 2,
> > + chip->dev_cfg->reg_sense, val);
> > + }
> > + mutex_unlock(&chip->mutex);
> > +}
> > +
> > +static irqreturn_t sx150x_irq_thread_fn(int irq, void *dev_id)
> > +{
> > + struct sx150x_chip *chip = (struct sx150x_chip *)dev_id;
> > + int i;
> > + unsigned n;
> > + unsigned sub_irq;
> > + u8 val;
> > + unsigned nhandled = 0;
> > +
> > + mutex_lock(&chip->mutex);
> > + for (i = (chip->dev_cfg->ngpios / 8) - 1; i >= 0; --i) {
> > + sx150x_i2c_read(chip->client,
> > + chip->dev_cfg->reg_irq_src - i,
> > + &val);
> > + sx150x_i2c_write(chip->client,
> > + chip->dev_cfg->reg_irq_src - i,
> > + val);

val may be used uninitialized here, if sx150x_i2c_read() failed.

> > + for (n = 0; n < 8; ++n) {
> > + if (val & (1 << n)) {
> > + sub_irq = chip->irq_base + (i * 8) + n;
> > + handle_nested_irq(sub_irq);
> > + ++nhandled;
> > + }
> > + }
> > + }
> > + mutex_unlock(&chip->mutex);
> > +
> > + return (nhandled > 0 ? IRQ_HANDLED : IRQ_NONE);
> > +}
> > +
> > +static void sx150x_init_chip(struct sx150x_chip *chip,
> > + struct i2c_client *client,
> > + kernel_ulong_t driver_data,
> > + struct sx150x_platform_data *pdata)
> > +{
> > + mutex_init(&chip->mutex);
> > +
> > + chip->client = client;
> > + chip->dev_cfg = &sx150x_devices[driver_data];
> > + chip->gpio_chip.label = client->name;
> > + chip->gpio_chip.direction_input = sx150x_gpio_direction_input;
> > + chip->gpio_chip.direction_output = sx150x_gpio_direction_output;
> > + chip->gpio_chip.get = sx150x_gpio_get;
> > + chip->gpio_chip.set = sx150x_gpio_set;
> > + chip->gpio_chip.to_irq = sx150x_gpio_to_irq;
> > + chip->gpio_chip.base = pdata->gpio_base;
> > + chip->gpio_chip.can_sleep = 1;
> > + chip->gpio_chip.ngpio = chip->dev_cfg->ngpios;
> > + if (pdata->oscio_is_gpo)
> > + ++chip->gpio_chip.ngpio;
> > +
> > + chip->irq_chip.name = client->name;
> > + chip->irq_chip.mask = sx150x_irq_mask;
> > + chip->irq_chip.unmask = sx150x_irq_unmask;
> > + chip->irq_chip.set_type = sx150x_irq_set_type;
>
> Why we are not using bus_lock/unlock hooks?
>
> > + chip->irq_summary = -1;
> > + chip->irq_base = -1;
> > + chip->irq_sense = 0;
> > +
> > + bitmap_zero(chip->irq_cmds, NCMDBITS);
> > +
> > + INIT_WORK(&chip->irq_mask_ws, sx150x_irq_mask_wfn);
> > + INIT_WORK(&chip->irq_unmask_ws, sx150x_irq_unmask_wfn);
> > + INIT_WORK(&chip->irq_set_type_ws, sx150x_irq_set_type_wfn);
> > +}
> > +
> > +static int sx150x_init_io(struct sx150x_chip *chip, u8 base, u16 cfg)
> > +{
> > + int err = 0;
> > + unsigned n;
> > +
> > + for (n = 0; err >= 0 && n < (chip->dev_cfg->ngpios / 8); ++n)
> > + err = sx150x_i2c_write(chip->client, base - n, cfg >> (n * 8));
> > + return err;
> > +}
> > +
> > +static int sx150x_init_hw(struct sx150x_chip *chip,
> > + struct sx150x_platform_data *pdata)
> > +{
> > + int err = 0;
> > +
> > + err = i2c_smbus_write_word_data(chip->client,
> > + chip->dev_cfg->reg_reset,
> > + 0x3412);
> > + if (err < 0)
> > + return err;
> > +
> > + err = sx150x_i2c_write(chip->client,
> > + chip->dev_cfg->reg_misc,
> > + 0x01);
> > + if (err < 0)
> > + return err;
> > +
> > + err = sx150x_init_io(chip, chip->dev_cfg->reg_pullup,
> > + pdata->io_pullup_ena);
> > + if (err < 0)
> > + return err;
> > +
> > + err = sx150x_init_io(chip, chip->dev_cfg->reg_pulldn,
> > + pdata->io_pulldn_ena);
> > + if (err < 0)
> > + return err;
> > +
> > + err = sx150x_init_io(chip, chip->dev_cfg->reg_drain,
> > + pdata->io_open_drain_ena);
> > + if (err < 0)
> > + return err;
> > +
> > + err = sx150x_init_io(chip, chip->dev_cfg->reg_polarity,
> > + pdata->io_polarity);
> > + if (err < 0)
> > + return err;
> > +
> > + if (pdata->oscio_is_gpo)
> > + sx150x_set_oscio(chip, 0);
> > +
> > + return err;
> > +}
> > +
> > +static int sx150x_install_irq_chip(struct sx150x_chip *chip,
> > + int irq_summary,
> > + int irq_base)
> > +{
> > + int err;
> > + unsigned n;
> > + unsigned irq;
> > +
> > + chip->irq_summary = irq_summary;
> > + chip->irq_base = irq_base;
> > +
> > + for (n = 0; n < chip->dev_cfg->ngpios; ++n) {
> > + irq = irq_base + n;
> > + set_irq_chip_and_handler(irq, &chip->irq_chip, handle_edge_irq);
> > + set_irq_nested_thread(irq, 1);
> > +#ifdef CONFIG_ARM
> > + set_irq_flags(irq, IRQF_VALID);
> > +#else
> > + set_irq_noprobe(irq);
> > +#endif
> > + }
> > +
> > + err = request_threaded_irq(irq_summary,
> > + NULL,
> > + sx150x_irq_thread_fn,
> > + IRQF_SHARED | IRQF_TRIGGER_FALLING,
> > + chip->irq_chip.name,
> > + chip);
> > + if (err < 0) {
> > + chip->irq_summary = -1;
> > + chip->irq_base = -1;
> > + }
> > +
> > + return err;
> > +}
> > +
> > +static void sx150x_remove_irq_chip(struct sx150x_chip *chip)
> > +{
> > + unsigned n;
> > + unsigned irq;
> > +
> > + free_irq(chip->irq_summary, chip);
> > +
> > + for (n = 0; n < chip->dev_cfg->ngpios; ++n) {
> > + irq = gpio_to_irq(chip->gpio_chip.base + n);
> > + set_irq_handler(irq, NULL);
> > + set_irq_chip(irq, NULL);
> > + }
> > +}
> > +
> > +static int __devinit sx150x_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id)
> > +{
> > + struct sx150x_platform_data *pdata;
> > + struct sx150x_chip *chip;
> > + int rc;
> > +
> > + pdata = client->dev.platform_data;
> > + if (!pdata)
> > + return -EINVAL;
> > +
> > + if (!i2c_check_functionality(client->adapter,
> > + I2C_FUNC_SMBUS_BYTE_DATA))

Your driver is also making use of i2c_smbus_write_word_data(), so you
should check for its availability.

> > + return -ENOSYS;
> > +
> > + chip = kzalloc(sizeof(struct sx150x_chip), GFP_KERNEL);
> > + if (!chip)
> > + return -ENOMEM;
> > +
> > + sx150x_init_chip(chip, client, id->driver_data, pdata);
> > + rc = sx150x_init_hw(chip, pdata);
> > + if (rc < 0)
> > + goto probe_fail;
> > +
> > + rc = gpiochip_add(&chip->gpio_chip);
> > + if (rc < 0)
> > + goto probe_fail;
> > +
> > + i2c_set_clientdata(client, chip);
> > +
> > + if (pdata->irq_summary >= 0) {
> > + rc = sx150x_install_irq_chip(chip,
> > + pdata->irq_summary,
> > + pdata->irq_base);
> > + if (rc < 0)
> > + goto probe_fail;

Aren't you supposed to call gpiochip_remove() here?

> > + }
> > +
> > + return 0;
> > +probe_fail:
> > + kfree(chip);
> > + return rc;
> > +}
> > +
> > +static int __devexit sx150x_remove(struct i2c_client *client)
> > +{
> > + struct sx150x_chip *chip;
> > + int rc;
> > +
> > + chip = i2c_get_clientdata(client);
> > + rc = gpiochip_remove(&chip->gpio_chip);
> > + if (rc < 0)
> > + return rc;
> > +
> > + if (chip->irq_summary >= 0)
> > + sx150x_remove_irq_chip(chip);
> > +
> > + flush_work(&chip->irq_mask_ws);
> > + flush_work(&chip->irq_unmask_ws);
> > + flush_work(&chip->irq_set_type_ws);
> > + kfree(chip);
> > +
> > + return rc;

Note: rc can only be 0 here.

> > +}
> > +
> > +static struct i2c_driver sx150x_driver = {
> > + .driver = {
> > + .name = "sx150x",
> > + .owner = THIS_MODULE
> > + },
> > + .probe = sx150x_probe,
> > + .remove = __devexit_p(sx150x_remove),
> > + .id_table = sx150x_id,
> > +};
> > +
> > +static int __init sx150x_init(void)
> > +{
> > + return i2c_add_driver(&sx150x_driver);
> > +}
> > +subsys_initcall(sx150x_init);
> > +
> > +static void __exit sx150x_exit(void)
> > +{
> > + return i2c_del_driver(&sx150x_driver);
> > +}
> > +module_exit(sx150x_exit);
> > +
> > +MODULE_AUTHOR("Gregory Bean <gbean(a)codeaurora.org>");
> > +MODULE_DESCRIPTION("Driver for Semtech SX150X I2C GPIO Expanders");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_ALIAS("platform:sx150x");

Looks wrong, as this isn't a platform driver but an i2c driver.

--
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From: Marc Zyngier on 21 Jul 2010 05:50
On Tue, 20 Jul 2010 14:07:43 -0700
Gregory Bean <gbean(a)codeaurora.org> wrote:

Gregory,

> Add support for Semtech SX150-series I2C GPIO expanders.
> Compatible models include:
>
> 8 bits: sx1508q
> 16 bits: sx1509q
>
> Signed-off-by: Gregory Bean <gbean(a)codeaurora.org>

> +static int sx150x_irq_set_type(unsigned int irq, unsigned int flow_type)
> +{
> + struct irq_chip *ic = get_irq_chip(irq);
> + struct sx150x_chip *chip;
> + unsigned n, val = 0;
> +
> + if (flow_type & (IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_LEVEL_LOW))
> + return -EINVAL;
> +
> + chip = container_of(ic, struct sx150x_chip, irq_chip);
> + n = irq - chip->irq_base;
> +
> + if (flow_type & IRQ_TYPE_EDGE_RISING)
> + val |= 0x1;
> + if (flow_type & IRQ_TYPE_EDGE_FALLING)
> + val |= 0x2;
> +
> + mutex_lock(&chip->mutex);
> + chip->irq_sense &= ~(3UL << (n * 2));
> + chip->irq_sense |= val << (n * 2);
> + if (!(irq_to_desc(irq)->status & IRQ_MASKED))
> + sx150x_write_cfg(chip, n, 2, chip->dev_cfg->reg_sense, val);
> + mutex_unlock(&chip->mutex);
> +
> + return 0;
> +}

Several problems here:
* This can be called from request_threaded irq(), which means the mutex
is already taken (via the bus_lock method).
* On the same path, __setup_irq will disable local interrupts before
calling this function. Bad things will happen if your I2C controller
wants to sleep. pca953x had the same problem, see
a2cb9aeb3c9b2475955cec328487484034f414e4 for a potential solution.

> +static irqreturn_t sx150x_irq_thread_fn(int irq, void *dev_id)
> +{
> + struct sx150x_chip *chip = (struct sx150x_chip *)dev_id;
> + unsigned nhandled = 0;
> + unsigned sub_irq;
> + unsigned n;
> + s32 err;
> + u8 val;
> + int i;
> +
> + mutex_lock(&chip->mutex);

This looks wrong... The whole purpose of the genirq framework is that it
takes care of most of the locking for you if you provide the
bus_lock/unlock methods. You should only use direct locking to protect
against races from the gpiolib framework.

> + for (i = (chip->dev_cfg->ngpios / 8) - 1; i >= 0; --i) {
> + err = sx150x_i2c_read(chip->client,
> + chip->dev_cfg->reg_irq_src - i,
> + &val);
> + if (err < 0)
> + continue;
> +
> + sx150x_i2c_write(chip->client,
> + chip->dev_cfg->reg_irq_src - i,
> + val);
> + for (n = 0; n < 8; ++n) {
> + if (val & (1 << n)) {
> + sub_irq = chip->irq_base + (i * 8) + n;
> + handle_nested_irq(sub_irq);
> + ++nhandled;
> + }
> + }
> + }
> + mutex_unlock(&chip->mutex);
> +
> + return (nhandled > 0 ? IRQ_HANDLED : IRQ_NONE);
> +}
> +

Cheers,

M.
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From: Randy Dunlap on 22 Jul 2010 13:20
On Thu, 22 Jul 2010 10:12:51 -0700 Gregory Bean wrote:

> drivers/gpio/Kconfig | 11 +
> drivers/gpio/Makefile | 1 +
> drivers/gpio/sx150x.c | 645 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/i2c/sx150x.h | 78 ++++++
> 4 files changed, 735 insertions(+), 0 deletions(-)
> create mode 100644 drivers/gpio/sx150x.c
> create mode 100644 include/linux/i2c/sx150x.h
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 7face91..f623953 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -195,6 +195,17 @@ config GPIO_PCF857X
> This driver provides an in-kernel interface to those GPIOs using
> platform-neutral GPIO calls.
>
> +config GPIO_SX150X
> + bool "Semtech SX150x I2C GPIO expander"
> + depends on I2C=y
> + default n
> + help
> + Say yes here to provide support for Semtech SX150-series I2C
> + GPIO expanders. Compatible models include:

Just curious, not complaining, but why does this driver (and some others)
need to be built-in instead of having the option of being built as a
loadable module?


> + 8 bits: sx1508q
> + 16 bits: sx1509q
> +
> config GPIO_TC35892
> bool "TC35892 GPIOs"
> depends on MFD_TC35892




---
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
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From: Greg Bean on 22 Jul 2010 13:30
>> + bool "Semtech SX150x I2C GPIO expander"
>> + depends on I2C=y
>> + default n
>> + help
>> + Say yes here to provide support for Semtech SX150-series I2C
>> + GPIO expanders. Compatible models include:
>
> Just curious, not complaining, but why does this driver (and some others)
> need to be built-in instead of having the option of being built as a
> loadable module?

It's that way because it requires unexported symbols from genirq and
I2C. If this driver is allowed to be a module, it can't find the
unexported genirq symbols, and if I2C is allowed to be a module, then a
bunch of i2c_smbus stuff can't be resolved...

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