[PATCH] reorg RTAS delay code
Nathan Lynch
ntl at pobox.com
Tue Jun 6 07:54:40 EST 2006
John Rose wrote:
> This patch attempts to handle RTAS "busy" return codes in a more simple
> and consistent manner. Typical callers of RTAS shouldn't have to
> manage wait times and delay calls.
>
> This patch also changes the kernel to use msleep() rather than udelay()
> when a runtime delay is necessary. This will avoid CPU soft lockups
> for extended delay conditions.
>
> Signed-off-by: John Rose <johnrose at austin.ibm.com>
>
> ---
>
> Resend - added the suggested might_sleep() and braces.
FWIW:
Acked-by: Nathan Lynch <ntl at pobox.com>
> 2_6_linus-johnrose/arch/powerpc/kernel/rtas-rtc.c | 30 +++----
> 2_6_linus-johnrose/arch/powerpc/kernel/rtas.c | 85 ++++++++------------
> 2_6_linus-johnrose/arch/powerpc/kernel/rtas_flash.c | 25 -----
> 2_6_linus-johnrose/include/asm-powerpc/rtas.h | 8 -
> 4 files changed, 57 insertions(+), 91 deletions(-)
>
> diff -puN arch/powerpc/kernel/rtas.c~rtas_delay_reorg arch/powerpc/kernel/rtas.c
> --- 2_6_linus/arch/powerpc/kernel/rtas.c~rtas_delay_reorg 2006-06-02 15:09:43.000000000 -0500
> +++ 2_6_linus-johnrose/arch/powerpc/kernel/rtas.c 2006-06-05 15:00:03.000000000 -0500
> @@ -370,24 +370,36 @@ int rtas_call(int token, int nargs, int
> return ret;
> }
>
> -/* Given an RTAS status code of 990n compute the hinted delay of 10^n
> - * (last digit) milliseconds. For now we bound at n=5 (100 sec).
> +/* For RTAS_BUSY (-2), delay for 1 millisecond. For an extended busy status
> + * code of 990n, perform the hinted delay of 10^n (last digit) milliseconds.
> */
> -unsigned int rtas_extended_busy_delay_time(int status)
> +unsigned int rtas_busy_delay_time(int status)
> {
> - int order = status - 9900;
> - unsigned long ms;
> + int order;
> + unsigned int ms = 0;
>
> - if (order < 0)
> - order = 0; /* RTC depends on this for -2 clock busy */
> - else if (order > 5)
> - order = 5; /* bound */
> + if (status == RTAS_BUSY) {
> + ms = 1;
> + } else if (status >= 9900 && status <= 9905) {
> + order = status - 9900;
> + for (ms = 1; order > 0; order--)
> + ms *= 10;
> + }
> +
> + return ms;
> +}
> +
> +/* For an RTAS busy status code, perform the hinted delay. */
> +unsigned int rtas_busy_delay(int status)
> +{
> + unsigned int ms;
>
> - /* Use microseconds for reasonable accuracy */
> - for (ms = 1; order > 0; order--)
> - ms *= 10;
> + might_sleep();
> + ms = rtas_busy_delay_time(status);
> + if (ms)
> + msleep(ms);
>
> - return ms;
> + return ms;
> }
>
> int rtas_error_rc(int rtas_rc)
> @@ -438,22 +450,14 @@ int rtas_get_power_level(int powerdomain
> int rtas_set_power_level(int powerdomain, int level, int *setlevel)
> {
> int token = rtas_token("set-power-level");
> - unsigned int wait_time;
> int rc;
>
> if (token == RTAS_UNKNOWN_SERVICE)
> return -ENOENT;
>
> - while (1) {
> + do {
> rc = rtas_call(token, 2, 2, setlevel, powerdomain, level);
> - if (rc == RTAS_BUSY)
> - udelay(1);
> - else if (rtas_is_extended_busy(rc)) {
> - wait_time = rtas_extended_busy_delay_time(rc);
> - udelay(wait_time * 1000);
> - } else
> - break;
> - }
> + } while (rtas_busy_delay(rc));
>
> if (rc < 0)
> return rtas_error_rc(rc);
> @@ -463,22 +467,14 @@ int rtas_set_power_level(int powerdomain
> int rtas_get_sensor(int sensor, int index, int *state)
> {
> int token = rtas_token("get-sensor-state");
> - unsigned int wait_time;
> int rc;
>
> if (token == RTAS_UNKNOWN_SERVICE)
> return -ENOENT;
>
> - while (1) {
> + do {
> rc = rtas_call(token, 2, 2, state, sensor, index);
> - if (rc == RTAS_BUSY)
> - udelay(1);
> - else if (rtas_is_extended_busy(rc)) {
> - wait_time = rtas_extended_busy_delay_time(rc);
> - udelay(wait_time * 1000);
> - } else
> - break;
> - }
> + } while (rtas_busy_delay(rc));
>
> if (rc < 0)
> return rtas_error_rc(rc);
> @@ -488,23 +484,14 @@ int rtas_get_sensor(int sensor, int inde
> int rtas_set_indicator(int indicator, int index, int new_value)
> {
> int token = rtas_token("set-indicator");
> - unsigned int wait_time;
> int rc;
>
> if (token == RTAS_UNKNOWN_SERVICE)
> return -ENOENT;
>
> - while (1) {
> + do {
> rc = rtas_call(token, 3, 1, NULL, indicator, index, new_value);
> - if (rc == RTAS_BUSY)
> - udelay(1);
> - else if (rtas_is_extended_busy(rc)) {
> - wait_time = rtas_extended_busy_delay_time(rc);
> - udelay(wait_time * 1000);
> - }
> - else
> - break;
> - }
> + } while (rtas_busy_delay(rc));
>
> if (rc < 0)
> return rtas_error_rc(rc);
> @@ -555,13 +542,11 @@ void rtas_os_term(char *str)
> do {
> status = rtas_call(rtas_token("ibm,os-term"), 1, 1, NULL,
> __pa(rtas_os_term_buf));
> + } while (rtas_busy_delay(status));
>
> - if (status == RTAS_BUSY)
> - udelay(1);
> - else if (status != 0)
> - printk(KERN_EMERG "ibm,os-term call failed %d\n",
> + if (status != 0)
> + printk(KERN_EMERG "ibm,os-term call failed %d\n",
> status);
> - } while (status == RTAS_BUSY);
> }
>
> static int ibm_suspend_me_token = RTAS_UNKNOWN_SERVICE;
> @@ -789,7 +774,7 @@ EXPORT_SYMBOL(rtas_token);
> EXPORT_SYMBOL(rtas_call);
> EXPORT_SYMBOL(rtas_data_buf);
> EXPORT_SYMBOL(rtas_data_buf_lock);
> -EXPORT_SYMBOL(rtas_extended_busy_delay_time);
> +EXPORT_SYMBOL(rtas_busy_delay_time);
> EXPORT_SYMBOL(rtas_get_sensor);
> EXPORT_SYMBOL(rtas_get_power_level);
> EXPORT_SYMBOL(rtas_set_power_level);
> diff -puN arch/powerpc/kernel/rtas-rtc.c~rtas_delay_reorg arch/powerpc/kernel/rtas-rtc.c
> --- 2_6_linus/arch/powerpc/kernel/rtas-rtc.c~rtas_delay_reorg 2006-06-02 15:09:43.000000000 -0500
> +++ 2_6_linus-johnrose/arch/powerpc/kernel/rtas-rtc.c 2006-06-02 15:09:43.000000000 -0500
> @@ -14,19 +14,20 @@
> unsigned long __init rtas_get_boot_time(void)
> {
> int ret[8];
> - int error, wait_time;
> + int error;
> + unsigned int wait_time;
> u64 max_wait_tb;
>
> max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
> do {
> error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
> - if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
> - wait_time = rtas_extended_busy_delay_time(error);
> +
> + wait_time = rtas_busy_delay_time(error);
> + if (wait_time) {
> /* This is boot time so we spin. */
> udelay(wait_time*1000);
> - error = RTAS_CLOCK_BUSY;
> }
> - } while (error == RTAS_CLOCK_BUSY && (get_tb() < max_wait_tb));
> + } while (wait_time && (get_tb() < max_wait_tb));
>
> if (error != 0 && printk_ratelimit()) {
> printk(KERN_WARNING "error: reading the clock failed (%d)\n",
> @@ -44,24 +45,25 @@ unsigned long __init rtas_get_boot_time(
> void rtas_get_rtc_time(struct rtc_time *rtc_tm)
> {
> int ret[8];
> - int error, wait_time;
> + int error;
> + unsigned int wait_time;
> u64 max_wait_tb;
>
> max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
> do {
> error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
> - if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
> +
> + wait_time = rtas_busy_delay_time(error);
> + if (wait_time) {
> if (in_interrupt() && printk_ratelimit()) {
> memset(rtc_tm, 0, sizeof(struct rtc_time));
> printk(KERN_WARNING "error: reading clock"
> " would delay interrupt\n");
> return; /* delay not allowed */
> }
> - wait_time = rtas_extended_busy_delay_time(error);
> msleep(wait_time);
> - error = RTAS_CLOCK_BUSY;
> }
> - } while (error == RTAS_CLOCK_BUSY && (get_tb() < max_wait_tb));
> + } while (wait_time && (get_tb() < max_wait_tb));
>
> if (error != 0 && printk_ratelimit()) {
> printk(KERN_WARNING "error: reading the clock failed (%d)\n",
> @@ -88,14 +90,14 @@ int rtas_set_rtc_time(struct rtc_time *t
> tm->tm_year + 1900, tm->tm_mon + 1,
> tm->tm_mday, tm->tm_hour, tm->tm_min,
> tm->tm_sec, 0);
> - if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
> +
> + wait_time = rtas_busy_delay_time(error);
> + if (wait_time) {
> if (in_interrupt())
> return 1; /* probably decrementer */
> - wait_time = rtas_extended_busy_delay_time(error);
> msleep(wait_time);
> - error = RTAS_CLOCK_BUSY;
> }
> - } while (error == RTAS_CLOCK_BUSY && (get_tb() < max_wait_tb));
> + } while (wait_time && (get_tb() < max_wait_tb));
>
> if (error != 0 && printk_ratelimit())
> printk(KERN_WARNING "error: setting the clock failed (%d)\n",
> diff -puN include/asm-powerpc/rtas.h~rtas_delay_reorg include/asm-powerpc/rtas.h
> --- 2_6_linus/include/asm-powerpc/rtas.h~rtas_delay_reorg 2006-06-02 15:09:43.000000000 -0500
> +++ 2_6_linus-johnrose/include/asm-powerpc/rtas.h 2006-06-02 15:09:43.000000000 -0500
> @@ -177,12 +177,8 @@ extern unsigned long rtas_get_boot_time(
> extern void rtas_get_rtc_time(struct rtc_time *rtc_time);
> extern int rtas_set_rtc_time(struct rtc_time *rtc_time);
>
> -/* Given an RTAS status code of 9900..9905 compute the hinted delay */
> -unsigned int rtas_extended_busy_delay_time(int status);
> -static inline int rtas_is_extended_busy(int status)
> -{
> - return status >= 9900 && status <= 9909;
> -}
> +extern unsigned int rtas_busy_delay_time(int status);
> +extern unsigned int rtas_busy_delay(int status);
>
> extern void pSeries_log_error(char *buf, unsigned int err_type, int fatal);
>
> diff -puN arch/powerpc/kernel/rtas_flash.c~rtas_delay_reorg arch/powerpc/kernel/rtas_flash.c
> --- 2_6_linus/arch/powerpc/kernel/rtas_flash.c~rtas_delay_reorg 2006-06-02 15:09:43.000000000 -0500
> +++ 2_6_linus-johnrose/arch/powerpc/kernel/rtas_flash.c 2006-06-05 15:00:44.000000000 -0500
> @@ -365,20 +365,12 @@ static int rtas_excl_release(struct inod
>
> static void manage_flash(struct rtas_manage_flash_t *args_buf)
> {
> - unsigned int wait_time;
> s32 rc;
>
> - while (1) {
> + do {
> rc = rtas_call(rtas_token("ibm,manage-flash-image"), 1,
> 1, NULL, args_buf->op);
> - if (rc == RTAS_RC_BUSY)
> - udelay(1);
> - else if (rtas_is_extended_busy(rc)) {
> - wait_time = rtas_extended_busy_delay_time(rc);
> - udelay(wait_time * 1000);
> - } else
> - break;
> - }
> + } while (rtas_busy_delay(rc));
>
> args_buf->status = rc;
> }
> @@ -451,27 +443,18 @@ static ssize_t manage_flash_write(struct
> static void validate_flash(struct rtas_validate_flash_t *args_buf)
> {
> int token = rtas_token("ibm,validate-flash-image");
> - unsigned int wait_time;
> int update_results;
> s32 rc;
>
> rc = 0;
> - while(1) {
> + do {
> spin_lock(&rtas_data_buf_lock);
> memcpy(rtas_data_buf, args_buf->buf, VALIDATE_BUF_SIZE);
> rc = rtas_call(token, 2, 2, &update_results,
> (u32) __pa(rtas_data_buf), args_buf->buf_size);
> memcpy(args_buf->buf, rtas_data_buf, VALIDATE_BUF_SIZE);
> spin_unlock(&rtas_data_buf_lock);
> -
> - if (rc == RTAS_RC_BUSY)
> - udelay(1);
> - else if (rtas_is_extended_busy(rc)) {
> - wait_time = rtas_extended_busy_delay_time(rc);
> - udelay(wait_time * 1000);
> - } else
> - break;
> - }
> + } while (rtas_busy_delay(rc));
>
> args_buf->status = rc;
> args_buf->update_results = update_results;
>
> _
>
>
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