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Commit 734796f1 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
Browse files

powerpc/pmac/smp: Fix CPU hotplug crashes on some machines 



On some machines that use i2c to synchronize the timebases (such
as PowerMac7,2/7,3 G5 machines), hotplug CPU would crash when
putting back a new CPU online due to the underlying i2c bus being
closed.

This uses the newly added bringup_done() callback to move the close
along with other housekeeping calls, and adds a CPU notifier to
re-open the i2c bus around subsequent hotplug operations

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent d7294445

arch/powerpc/platforms/powermac/smp.c

+55 −16
Original line number Diff line number Diff line
@@ -840,31 +840,69 @@ static void __devinit smp_core99_setup_cpu(int cpu_nr) 


	/* Setup openpic */

	mpic_setup_this_cpu();

}



#ifdef CONFIG_HOTPLUG_CPU

static int smp_core99_cpu_notify(struct notifier_block *self,

				 unsigned long action, void *hcpu)

{

	int rc;



	if (cpu_nr == 0) {

	switch(action) {

	case CPU_UP_PREPARE:

	case CPU_UP_PREPARE_FROZEN:

		/* Open i2c bus if it was used for tb sync */

		if (pmac_tb_clock_chip_host) {

			rc = pmac_i2c_open(pmac_tb_clock_chip_host, 1);

			if (rc) {

				pr_err("Failed to open i2c bus for time sync\n");

				return notifier_from_errno(rc);

			}

		}

		break;

	case CPU_ONLINE:

	case CPU_UP_CANCELED:

		/* Close i2c bus if it was used for tb sync */

		if (pmac_tb_clock_chip_host)

			pmac_i2c_close(pmac_tb_clock_chip_host);

		break;

	default:

		break;

	}

	return NOTIFY_OK;

}



static struct notifier_block __cpuinitdata smp_core99_cpu_nb = {

	.notifier_call	= smp_core99_cpu_notify,

};

#endif /* CONFIG_HOTPLUG_CPU */



static void __init smp_core99_bringup_done(void)

{

#ifdef CONFIG_PPC64

	extern void g5_phy_disable_cpu1(void);



	/* Close i2c bus if it was used for tb sync */

		if (pmac_tb_clock_chip_host) {

	if (pmac_tb_clock_chip_host)

		pmac_i2c_close(pmac_tb_clock_chip_host);

			pmac_tb_clock_chip_host	= NULL;

		}



	/* If we didn't start the second CPU, we must take

		 * it off the bus

	 * it off the bus.

	 */

	if (of_machine_is_compatible("MacRISC4") &&

		    num_online_cpus() < 2)		

	    num_online_cpus() < 2) {

		set_cpu_present(1, false);

		g5_phy_disable_cpu1();

	}

#endif /* CONFIG_PPC64 */



#ifdef CONFIG_HOTPLUG_CPU

	register_cpu_notifier(&smp_core99_cpu_nb);

#endif

	if (ppc_md.progress)

			ppc_md.progress("core99_setup_cpu 0 done", 0x349);

	}

		ppc_md.progress("smp_core99_bringup_done", 0x349);

}





#ifdef CONFIG_HOTPLUG_CPU



static int smp_core99_cpu_disable(void)
@@ -940,6 +978,7 @@ static void pmac_cpu_die(void) 
struct smp_ops_t core99_smp_ops = {

	.message_pass	= smp_mpic_message_pass,

	.probe		= smp_core99_probe,

	.bringup_done	= smp_core99_bringup_done,

	.kick_cpu	= smp_core99_kick_cpu,

	.setup_cpu	= smp_core99_setup_cpu,

	.give_timebase	= smp_core99_give_timebase,