[PATCH 13/16] MIPS: BUS: CDMM: Convert to hotplug state machine

From: Sebastian Andrzej Siewior
Date: Thu Aug 18 2016 - 09:00:09 EST


Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: James Hogan <james.hogan@xxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
drivers/bus/mips_cdmm.c | 70 +++++++++----------------------------------------
1 file changed, 12 insertions(+), 58 deletions(-)

diff --git a/drivers/bus/mips_cdmm.c b/drivers/bus/mips_cdmm.c
index cad49bc38b3e..4e1e1ba51662 100644
--- a/drivers/bus/mips_cdmm.c
+++ b/drivers/bus/mips_cdmm.c
@@ -596,19 +596,20 @@ BUILD_PERDEV_HELPER(cpu_down) /* int mips_cdmm_cpu_down_helper(...) */
BUILD_PERDEV_HELPER(cpu_up) /* int mips_cdmm_cpu_up_helper(...) */

/**
- * mips_cdmm_bus_down() - Tear down the CDMM bus.
- * @data: Pointer to unsigned int CPU number.
+ * mips_cdmm_cpu_down_prep() - Callback for CPUHP DOWN_PREP:
+ * Tear down the CDMM bus.
+ * @cpu: unsigned int CPU number.
*
* This function is executed on the hotplugged CPU and calls the CDMM
* driver cpu_down callback for all devices on that CPU.
*/
-static long mips_cdmm_bus_down(void *data)
+static int mips_cdmm_cpu_down_prep(unsigned int cpu)
{
struct mips_cdmm_bus *bus;
long ret;

/* Inform all the devices on the bus */
- ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data,
+ ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, &cpu,
mips_cdmm_cpu_down_helper);

/*
@@ -623,8 +624,8 @@ static long mips_cdmm_bus_down(void *data)
}

/**
- * mips_cdmm_bus_up() - Bring up the CDMM bus.
- * @data: Pointer to unsigned int CPU number.
+ * mips_cdmm_cpu_online() - Callback for CPUHP ONLINE: Bring up the CDMM bus.
+ * @cpu: unsigned int CPU number.
*
* This work_on_cpu callback function is executed on a given CPU to discover
* CDMM devices on that CPU, or to call the CDMM driver cpu_up callback for all
@@ -634,7 +635,7 @@ static long mips_cdmm_bus_down(void *data)
* initialisation. When CPUs are brought online the function is
* invoked directly on the hotplugged CPU.
*/
-static long mips_cdmm_bus_up(void *data)
+static int mips_cdmm_cpu_online(unsigned int cpu)
{
struct mips_cdmm_bus *bus;
long ret;
@@ -651,51 +652,13 @@ static long mips_cdmm_bus_up(void *data)
mips_cdmm_bus_discover(bus);
else
/* Inform all the devices on the bus */
- ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data,
+ ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, &cpu,
mips_cdmm_cpu_up_helper);

return ret;
}

/**
- * mips_cdmm_cpu_notify() - Take action when a CPU is going online or offline.
- * @nb: CPU notifier block .
- * @action: Event that has taken place (CPU_*).
- * @data: CPU number.
- *
- * This notifier is used to keep the CDMM buses updated as CPUs are offlined and
- * onlined. When CPUs go offline or come back online, so does their CDMM bus, so
- * devices must be informed. Also when CPUs come online for the first time the
- * devices on the CDMM bus need discovering.
- *
- * Returns: NOTIFY_OK if event was used.
- * NOTIFY_DONE if we didn't care.
- */
-static int mips_cdmm_cpu_notify(struct notifier_block *nb,
- unsigned long action, void *data)
-{
- unsigned int cpu = (unsigned int)data;
-
- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_ONLINE:
- case CPU_DOWN_FAILED:
- mips_cdmm_bus_up(&cpu);
- break;
- case CPU_DOWN_PREPARE:
- mips_cdmm_bus_down(&cpu);
- break;
- default:
- return NOTIFY_DONE;
- }
-
- return NOTIFY_OK;
-}
-
-static struct notifier_block mips_cdmm_cpu_nb = {
- .notifier_call = mips_cdmm_cpu_notify,
-};
-
-/**
* mips_cdmm_init() - Initialise CDMM bus.
*
* Initialise CDMM bus, discover CDMM devices for online CPUs, and arrange for
@@ -703,7 +666,6 @@ static struct notifier_block mips_cdmm_cpu_nb = {
*/
static int __init mips_cdmm_init(void)
{
- unsigned int cpu;
int ret;

/* Register the bus */
@@ -712,19 +674,11 @@ static int __init mips_cdmm_init(void)
return ret;

/* We want to be notified about new CPUs */
- ret = register_cpu_notifier(&mips_cdmm_cpu_nb);
- if (ret) {
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "BUS_CDMM_ONLINE",
+ mips_cdmm_cpu_online, mips_cdmm_cpu_down_prep);
+ if (ret < 0)
pr_warn("cdmm: Failed to register CPU notifier\n");
- goto out;
- }

- /* Discover devices on CDMM of online CPUs */
- for_each_online_cpu(cpu)
- work_on_cpu(cpu, mips_cdmm_bus_up, &cpu);
-
- return 0;
-out:
- bus_unregister(&mips_cdmm_bustype);
return ret;
}
subsys_initcall(mips_cdmm_init);
--
2.9.3