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Message-Id: <20070227122606.8ec3f09a.akpm@linux-foundation.org>
Date: Tue, 27 Feb 2007 12:26:06 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Marc St-Jean <stjeanma@...-sierra.com>
Cc: linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org
Subject: Re: [PATCH] drivers: PMC MSP71xx GPIO char driver
> On Fri, 23 Feb 2007 17:28:19 -0600 Marc St-Jean <stjeanma@...-sierra.com> wrote:
> [PATCH] drivers: PMC MSP71xx GPIO char driver
>
> Patch to add a GPIO char driver for the PMC-Sierra
> MSP71xx devices.
>
> This patch references some platform support files previously
> submitted to the linux-mips@...ux-mips.org list.
>
Comments:
> +static int msp_blink_running;
Could have type `bool'.
> +static DEFINE_SPINLOCK(msp_blink_lock);
> +static DECLARE_COMPLETION(msp_blink_wait);
> +
> +struct blinkTable_t {
a) It uses StudlyCaps
b) the _t suffix is used for typedefs.
I suggest this be renamed to `struct blink_table'.
> + uint32_t count;
> + uint32_t period;
> + uint32_t dcycle;
u32 is preferred.
> +static uint32_t msp_gpio_read_data_extended(void)
everywhere...
> +{
> + int pin;
> + uint32_t tmp, retval = 0;
> +
> + tmp = *EXTENDED_GPIO_REG;
> + for( pin = 0; pin < EXTENDED_GPIO_COUNT; pin++ ) {
> + uint32_t bit = 0;
> + /*
> + * In output mode, read CLR bit
> + * In input mode, read SET bit
> + */
> + if( tmp & (EXTENDED_GPIO_CFG_ENABLE <<
> + EXTENDED_GPIO_CFG_SHIFT(pin)) )
Please convert all the code to sue standard whitespace conventions:
for (i = 0; i < n; i++) {
and
if (foo && bar)
> + bit = (EXTENDED_GPIO_DATA_CLR <<
> + EXTENDED_GPIO_DATA_SHIFT(pin));
Uneeded parens.
> + retval |= (1 << pin);
Ditto.
> +static int msp_gpio_ioctl( struct inode *inode, struct file *file,
> + unsigned int cmd, unsigned long arg)
> +{
> + static struct msp_gpio_ioctl_io_data data;
> + static struct msp_gpio_ioctl_blink_data blink;
> +
> + switch( cmd ) {
switch (cmd) {
> + case MSP_GPIO_BLINK:
> + if( copy_from_user(&blink, (struct msp_gpio_ioctl_blink_data *)arg, sizeof(blink) ) )
> + return -EFAULT;
> + break;
> + default:
> + if( copy_from_user(&data, (struct msp_gpio_ioctl_io_data *)arg, sizeof(data) ) )
> + return -EFAULT;
> + break;
Please indent the body of the switch one tabstop less than this.
Please fit all the code into 80-cols.
> + }
> +
> + switch( cmd ) {
> + case MSP_GPIO_IN:
> + if( msp_gpio_in( &data.data, data.mask ) )
Lots of dittos here.
> +/* -- Module functions -- */
> +
> +static int msp_gpio_blinkthread( void *none )
Why is this a "module function"?
> +{
> + int firstrun = 1;
> +
> + msp_blink_running = 1;
> + while( msp_blink_running ) {
> + uint32_t mask = 0, data = 0;
> + int i, blinking = 0;
> + spin_lock( &msp_blink_lock );
> + for( i = 0; i < MSP_NUM_GPIOS; i++ ) {
> + /* use blinkTable[i].period as 'blink enabled' test */
> + if( blinkTable[i].period) {
> + blinking = 1;
> + mask |= MSP_GPIO_BIT(i);
> + blinkTable[i].count++;
> +
> + if( blinkTable[i].count >=
> + blinkTable[i].period )
> + blinkTable[i].count = 0;
> +
> + if( blinkTable[i].count <
> + (blinkTable[i].period *
> + blinkTable[i].dcycle / 100 ) )
> + data |= MSP_GPIO_BIT(i);
> + }
> + }
> + spin_unlock( &msp_blink_lock );
> +
> + if( !firstrun || blinking )
> + msp_gpio_write_data( data, mask );
> + else
> + firstrun = 0;
> +
> + if( blinking ) {
> + set_current_state(TASK_INTERRUPTIBLE);
> + schedule_timeout (HZ/100);
schedule_timeout_interruptible), or ssleep().
This kernel thread will probably break suspend. I suspect a
try_to_freeze() is needed.
> + } else {
> + wait_for_completion_interruptible( &msp_blink_wait );
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int __init msp_gpio_init(void)
> +{
> + if( misc_register(&msp_gpio_miscdev) ) {
> + printk( "Device registration failed\n" );
> + goto err_miscdev;
> + }
> +
> + msp_blinkthread = kthread_run( msp_gpio_blinkthread, NULL, "gpio_blink" );
> + if( msp_blinkthread == NULL )
> + {
if (msp_blinkthread == NULL) {
> + printk( "Could not start kthread\n" );
> + goto err_blinkthread;
> + }
> +
> + printk( "MSP7120 GPIO subsystem initialized\n" );
Please give all the printks a facility level (KERN_INFO, etc)
> + return 0;
> +
> +err_blinkthread:
> + misc_deregister(&msp_gpio_miscdev);
> +err_miscdev:
> + return -ENOMEM;
> +}
> +
> +static void __exit msp_gpio_exit(void)
> +{
> + msp_blink_running = 0;
> + complete( &msp_blink_wait );
> + kthread_stop( msp_blinkthread );
> +
> + misc_deregister(&msp_gpio_miscdev);
> +}
I think msp_blink_running can just be removed - use kthread_should_stop().
> +module_init(msp_gpio_init);
> +module_exit(msp_gpio_exit);
> +
> +EXPORT_SYMBOL(msp_gpio_in);
> +EXPORT_SYMBOL(msp_gpio_out);
> +EXPORT_SYMBOL(msp_gpio_mode);
> +EXPORT_SYMBOL(msp_gpio_blink);
> +EXPORT_SYMBOL(msp_gpio_noblink);
What uses these exports?
> +#include <msp_gpio_macros.h>
> +
> +/* IOCTL structs macros */
> +
> +struct msp_gpio_ioctl_io_data
struct foo {
> +{
> + uint32_t data;
> + uint32_t mask;
> +};
> +
> +struct msp_gpio_ioctl_blink_data
> +{
Ditto.
> + uint32_t mask;
> + uint32_t period;
> + uint32_t dcycle;
> +};
> +
> +#define MSP_GPIO_IOCTL_BASE 'Z'
> +
> +/* Reads the current data bits */
> +#define MSP_GPIO_IN _IOWR(MSP_GPIO_IOCTL_BASE, 0, \
> + struct msp_gpio_ioctl_io_data )
Remvove space before the )
> +
> +/* Writes data bits */
> +#define MSP_GPIO_OUT _IOW (MSP_GPIO_IOCTL_BASE, 1, \
> + struct msp_gpio_ioctl_io_data )
> +
> +/*
> + * Sets all masked pins to the msp_gpio_mode_t given in the data field
> + */
> +#define MSP_GPIO_MODE _IOW (MSP_GPIO_IOCTL_BASE, 2, \
> + struct msp_gpio_ioctl_io_data )
Dittoes.
> +/*
> + * Starts any masked LEDs blinking with parameters as follows:
> + * - period - The time in 100ths of a second for a single period
> + * (set to '0' to stop blinking)
> + * - dcycle - The 'duty cycle' - what percentage of the period should the
> + * gpio be on?
> + */
> +#define MSP_GPIO_BLINK _IOW (MSP_GPIO_IOCTL_BASE, 3, \
> + struct msp_gpio_ioctl_blink_data )
And remove space before (
> +/* Bit flags and masks for GPIOs */
> +#define MSP_GPIO_BIT(gpio) (1 << gpio)
This probably obscures more than it reveals. Better to open-code it.
> +#define MSP_NUM_GPIOS (20)
> +
> +#define MSP_GPIO_ALL_MASK ((1<<MSP_NUM_GPIOS) - 1)
> +
> +#define MSP_GPIO_NONE_MASK (0LL)
> +
> +#define MSP_GPIO_FREE_MASK MSP_GPIO_ALL_MASK
> +
> +/* The following is only available to other modules */
> +
> +#ifdef __KERNEL__
> +
> +/*
> + * Reads the bits specified by the mask and puts the values in data.
> + * May include output statuses also, if in mask.
> + *
> + * Returns 0 on success
> + */
> +extern int msp_gpio_in( uint32_t *data, uint32_t mask );
Busted whitespace, use u32
> +
> +/*
> + * Sets the specified data to the masked pins
> + *
> + * Returns 0 on success or one of the following:
> + * -EINVAL if any of the pins in the mask are not free or not already in output
> + * mode
> + */
> +extern int msp_gpio_out( uint32_t data, uint32_t mask );
> +
> +/*
> + * Sets all masked pins to the specified msp_gpio_mode_t
> + *
> + * Returns 0 on success or one of the following:
> + * -EINVAL if any of the pins in the mask are not free, or if any pins are not
> + * allowed to be set to the specified mode
> + */
> +extern int msp_gpio_mode( msp_gpio_mode_t mode, uint32_t mask );
It's more conventional to document functions in the .c file, using
kerneldoc format.
> +/*
> + * Stops the specified GPIOs from blinking
> + */
> +extern int msp_gpio_noblink( uint32_t mask );
> +
> +/*
> + * Configures GPIO(s) to blink
> + * - mask shows which GPIOs to blink
> + * - period is the time in 100ths of a second for the total period
> + * (0 disables blinking)
> + * - dcycle is the percentage of the period where the GPIO is HI
> + */
> +int msp_gpio_blink( uint32_t mask, uint32_t period, uint32_t dcycle );
> +
> +/* Special bitflags and whatnot for the driver's convenience */
> +#define GPIO_REG_COUNT 4
> +const uint32_t GPIO_DATA_COUNT[] = { 2, 4, 4, 6 };
> +const uint32_t GPIO_DATA_SHIFT[] = { 0, 2, 6, 10 };
> +const uint32_t GPIO_DATA_MASK[] = { 0x03, 0x0f, 0x0f, 0x3f };
> +volatile uint32_t * const GPIO_DATA_REG[] = {
> + GPIO_DATA1_REG, GPIO_DATA2_REG, GPIO_DATA3_REG, GPIO_DATA4_REG,
> +};
> +const uint32_t GPIO_CFG_MASK[] = { 0x0000ff, 0x00ffff, 0x00ffff, 0xffffff };
> +volatile uint32_t * const GPIO_CFG_REG[] = {
> + GPIO_CFG1_REG, GPIO_CFG2_REG, GPIO_CFG3_REG, GPIO_CFG4_REG,
> +};
This should all be moved from .h into .c. As it is, if two .c files
include this header, we'll get additional copies of this data. And a
linker error.
Please don't use volatile. Kernel standard I/O operations (inb, readl,
etc) handle all this.
-
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