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ARM: brcmstb: update CPU power management sequence 

The automatic CPU power state machine for B15 CPUs does not work
reliably as-is. This patch implements a manual sequence in software to
replace it.

This was tested successfully with over 10,000 hotplug cycles of
something like this:

  echo 0 > /sys/devices/system/cpu/cpu1/online
  echo 1 > /sys/devices/system/cpu/cpu1/online

whereas the existing sequence often locks up after a few hundred cycles.

Fixes: 62639c2f53 ("ARM: brcmstb: reintroduce SMP support")
Acked-by: Gregory Fong <gregory.0xf0@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
This commit is contained in:
Brian Norris 2014-12-16 19:13:50 -08:00 committed by Florian Fainelli
parent 97bf6af1f9
commit a1ad3b94a7
1 changed files with 63 additions and 22 deletions
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85
arch/arm/mach-bcm/platsmp-brcmstb.c
View File

@ -17,6 +17,7 @@
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/jiffies.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/printk.h>
@ -94,10 +95,35 @@ static u32 pwr_ctrl_rd(u32 cpu)
return readl_relaxed(base);
}
static void pwr_ctrl_wr(u32 cpu, u32 val)
static void pwr_ctrl_set(unsigned int cpu, u32 val, u32 mask)
{
void __iomem *base = pwr_ctrl_get_base(cpu);
writel(val, base);
writel((readl(base) & mask) | val, base);
}
static void pwr_ctrl_clr(unsigned int cpu, u32 val, u32 mask)
{
void __iomem *base = pwr_ctrl_get_base(cpu);
writel((readl(base) & mask) & ~val, base);
}
#define POLL_TMOUT_MS 500
static int pwr_ctrl_wait_tmout(unsigned int cpu, u32 set, u32 mask)
{
const unsigned long timeo = jiffies + msecs_to_jiffies(POLL_TMOUT_MS);
u32 tmp;
do {
tmp = pwr_ctrl_rd(cpu) & mask;
if (!set == !tmp)
return 0;
} while (time_before(jiffies, timeo));
tmp = pwr_ctrl_rd(cpu) & mask;
if (!set == !tmp)
return 0;
return -ETIMEDOUT;
}
static void cpu_rst_cfg_set(u32 cpu, int set)
@ -139,15 +165,22 @@ static void brcmstb_cpu_power_on(u32 cpu)
* The secondary cores power was cut, so we must go through
* power-on initialization.
*/
u32 tmp;
pwr_ctrl_set(cpu, ZONE_MAN_ISO_CNTL_MASK, 0xffffff00);
pwr_ctrl_set(cpu, ZONE_MANUAL_CONTROL_MASK, -1);
pwr_ctrl_set(cpu, ZONE_RESERVED_1_MASK, -1);
/* Request zone power up */
pwr_ctrl_wr(cpu, ZONE_PWR_UP_REQ_MASK);
pwr_ctrl_set(cpu, ZONE_MAN_MEM_PWR_MASK, -1);
/* Wait for the power up FSM to complete */
do {
tmp = pwr_ctrl_rd(cpu);
} while (!(tmp & ZONE_PWR_ON_STATE_MASK));
if (pwr_ctrl_wait_tmout(cpu, 1, ZONE_MEM_PWR_STATE_MASK))
panic("ZONE_MEM_PWR_STATE_MASK set timeout");
pwr_ctrl_set(cpu, ZONE_MAN_CLKEN_MASK, -1);
if (pwr_ctrl_wait_tmout(cpu, 1, ZONE_DPG_PWR_STATE_MASK))
panic("ZONE_DPG_PWR_STATE_MASK set timeout");
pwr_ctrl_clr(cpu, ZONE_MAN_ISO_CNTL_MASK, -1);
pwr_ctrl_set(cpu, ZONE_MAN_RESET_CNTL_MASK, -1);
}
static int brcmstb_cpu_get_power_state(u32 cpu)
@ -174,25 +207,33 @@ static void brcmstb_cpu_die(u32 cpu)
static int brcmstb_cpu_kill(u32 cpu)
{
u32 tmp;
/*
* Ordinarily, the hardware forbids power-down of CPU0 (which is good
* because it is the boot CPU), but this is not true when using BPCM
* manual mode. Consequently, we must avoid turning off CPU0 here to
* ensure that TI2C master reset will work.
*/
if (cpu == 0) {
pr_warn("SMP: refusing to power off CPU0\n");
return 1;
}
while (per_cpu_sw_state_rd(cpu))
;
/* Program zone reset */
pwr_ctrl_wr(cpu, ZONE_RESET_STATE_MASK | ZONE_BLK_RST_ASSERT_MASK |
ZONE_PWR_DN_REQ_MASK);
pwr_ctrl_set(cpu, ZONE_MANUAL_CONTROL_MASK, -1);
pwr_ctrl_clr(cpu, ZONE_MAN_RESET_CNTL_MASK, -1);
pwr_ctrl_clr(cpu, ZONE_MAN_CLKEN_MASK, -1);
pwr_ctrl_set(cpu, ZONE_MAN_ISO_CNTL_MASK, -1);
pwr_ctrl_clr(cpu, ZONE_MAN_MEM_PWR_MASK, -1);
/* Verify zone reset */
tmp = pwr_ctrl_rd(cpu);
if (!(tmp & ZONE_RESET_STATE_MASK))
pr_err("%s: Zone reset bit for CPU %d not asserted!\n",
__func__, cpu);
if (pwr_ctrl_wait_tmout(cpu, 0, ZONE_MEM_PWR_STATE_MASK))
panic("ZONE_MEM_PWR_STATE_MASK clear timeout");
/* Wait for power down */
do {
tmp = pwr_ctrl_rd(cpu);
} while (!(tmp & ZONE_PWR_OFF_STATE_MASK));
pwr_ctrl_clr(cpu, ZONE_RESERVED_1_MASK, -1);
if (pwr_ctrl_wait_tmout(cpu, 0, ZONE_DPG_PWR_STATE_MASK))
panic("ZONE_DPG_PWR_STATE_MASK clear timeout");
/* Flush pipeline before resetting CPU */
mb();