ARM: tegra: cpuidle: Handle case where secondary CPU hangs on entering LP2

#include <linux/tick.h>

#include <linux/cpuidle.h>

#include <linux/cpu_pm.h>

#include <linux/delay.h>

#include <linux/kernel.h>

#include <linux/module.h>

}

#endif

static void tegra20_report_cpus_state(void)

{

	unsigned long cpu, lcpu, csr;

	for_each_cpu(lcpu, cpu_possible_mask) {

		cpu = cpu_logical_map(lcpu);

		csr = flowctrl_read_cpu_csr(cpu);

		pr_err("cpu%lu: online=%d flowctrl_csr=0x%08lx\n",

		       cpu, cpu_online(lcpu), csr);

	}

}

static int tegra20_wait_for_secondary_cpu_parking(void)

{

	unsigned int retries = 3;

	while (retries--) {

		unsigned int delay_us = 10;

		unsigned int timeout_us = 500 * 1000 / delay_us;

		/*

		 * The primary CPU0 core shall wait for the secondaries

		 * shutdown in order to power-off CPU's cluster safely.

		 * The timeout value depends on the current CPU frequency,

		 * it takes about 40-150us  in average and over 1000us in

		 * a worst case scenario.

		 */

		do {

			if (tegra_cpu_rail_off_ready())

				return 0;

			udelay(delay_us);

		} while (timeout_us--);

		pr_err("secondary CPU taking too long to park\n");

		tegra20_report_cpus_state();

	}

	pr_err("timed out waiting secondaries to park\n");

	return -ETIMEDOUT;

}

static bool tegra20_cpu_cluster_power_down(struct cpuidle_device *dev,

					   struct cpuidle_driver *drv,

					   int index)

{

	bool ret;

	while (!tegra_cpu_rail_off_ready())

		cpu_relax();

	if (tegra20_wait_for_secondary_cpu_parking())

		return false;

	ret = !tegra_pm_enter_lp2();