Initial import

1 files changed, 218 insertions, 0 deletions

diff --git a/drivers/cpufreq/tegra-cpufreq.c b/drivers/cpufreq/tegra-cpufreq.c
new file mode 100644
index 000000000..8084c7f7e
--- /dev/null
+++ b/drivers/cpufreq/tegra-cpufreq.c
@@ -0,0 +1,218 @@
+/*
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ *	Colin Cross <ccross@google.com>
+ *	Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/cpufreq.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+
+static struct cpufreq_frequency_table freq_table[] = {
+	{ .frequency = 216000 },
+	{ .frequency = 312000 },
+	{ .frequency = 456000 },
+	{ .frequency = 608000 },
+	{ .frequency = 760000 },
+	{ .frequency = 816000 },
+	{ .frequency = 912000 },
+	{ .frequency = 1000000 },
+	{ .frequency = CPUFREQ_TABLE_END },
+};
+
+#define NUM_CPUS	2
+
+static struct clk *cpu_clk;
+static struct clk *pll_x_clk;
+static struct clk *pll_p_clk;
+static struct clk *emc_clk;
+static bool pll_x_prepared;
+
+static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
+					   unsigned int index)
+{
+	unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
+
+	/*
+	 * Don't switch to intermediate freq if:
+	 * - we are already at it, i.e. policy->cur == ifreq
+	 * - index corresponds to ifreq
+	 */
+	if ((freq_table[index].frequency == ifreq) || (policy->cur == ifreq))
+		return 0;
+
+	return ifreq;
+}
+
+static int tegra_target_intermediate(struct cpufreq_policy *policy,
+				     unsigned int index)
+{
+	int ret;
+
+	/*
+	 * Take an extra reference to the main pll so it doesn't turn
+	 * off when we move the cpu off of it as enabling it again while we
+	 * switch to it from tegra_target() would take additional time.
+	 *
+	 * When target-freq is equal to intermediate freq we don't need to
+	 * switch to an intermediate freq and so this routine isn't called.
+	 * Also, we wouldn't be using pll_x anymore and must not take extra
+	 * reference to it, as it can be disabled now to save some power.
+	 */
+	clk_prepare_enable(pll_x_clk);
+
+	ret = clk_set_parent(cpu_clk, pll_p_clk);
+	if (ret)
+		clk_disable_unprepare(pll_x_clk);
+	else
+		pll_x_prepared = true;
+
+	return ret;
+}
+
+static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
+{
+	unsigned long rate = freq_table[index].frequency;
+	unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
+	int ret = 0;
+
+	/*
+	 * Vote on memory bus frequency based on cpu frequency
+	 * This sets the minimum frequency, display or avp may request higher
+	 */
+	if (rate >= 816000)
+		clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
+	else if (rate >= 456000)
+		clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
+	else
+		clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
+
+	/*
+	 * target freq == pll_p, don't need to take extra reference to pll_x_clk
+	 * as it isn't used anymore.
+	 */
+	if (rate == ifreq)
+		return clk_set_parent(cpu_clk, pll_p_clk);
+
+	ret = clk_set_rate(pll_x_clk, rate * 1000);
+	/* Restore to earlier frequency on error, i.e. pll_x */
+	if (ret)
+		pr_err("Failed to change pll_x to %lu\n", rate);
+
+	ret = clk_set_parent(cpu_clk, pll_x_clk);
+	/* This shouldn't fail while changing or restoring */
+	WARN_ON(ret);
+
+	/*
+	 * Drop count to pll_x clock only if we switched to intermediate freq
+	 * earlier while transitioning to a target frequency.
+	 */
+	if (pll_x_prepared) {
+		clk_disable_unprepare(pll_x_clk);
+		pll_x_prepared = false;
+	}
+
+	return ret;
+}
+
+static int tegra_cpu_init(struct cpufreq_policy *policy)
+{
+	int ret;
+
+	if (policy->cpu >= NUM_CPUS)
+		return -EINVAL;
+
+	clk_prepare_enable(emc_clk);
+	clk_prepare_enable(cpu_clk);
+
+	/* FIXME: what's the actual transition time? */
+	ret = cpufreq_generic_init(policy, freq_table, 300 * 1000);
+	if (ret) {
+		clk_disable_unprepare(cpu_clk);
+		clk_disable_unprepare(emc_clk);
+		return ret;
+	}
+
+	policy->clk = cpu_clk;
+	policy->suspend_freq = freq_table[0].frequency;
+	return 0;
+}
+
+static int tegra_cpu_exit(struct cpufreq_policy *policy)
+{
+	clk_disable_unprepare(cpu_clk);
+	clk_disable_unprepare(emc_clk);
+	return 0;
+}
+
+static struct cpufreq_driver tegra_cpufreq_driver = {
+	.flags			= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify			= cpufreq_generic_frequency_table_verify,
+	.get_intermediate	= tegra_get_intermediate,
+	.target_intermediate	= tegra_target_intermediate,
+	.target_index		= tegra_target,
+	.get			= cpufreq_generic_get,
+	.init			= tegra_cpu_init,
+	.exit			= tegra_cpu_exit,
+	.name			= "tegra",
+	.attr			= cpufreq_generic_attr,
+#ifdef CONFIG_PM
+	.suspend		= cpufreq_generic_suspend,
+#endif
+};
+
+static int __init tegra_cpufreq_init(void)
+{
+	cpu_clk = clk_get_sys(NULL, "cclk");
+	if (IS_ERR(cpu_clk))
+		return PTR_ERR(cpu_clk);
+
+	pll_x_clk = clk_get_sys(NULL, "pll_x");
+	if (IS_ERR(pll_x_clk))
+		return PTR_ERR(pll_x_clk);
+
+	pll_p_clk = clk_get_sys(NULL, "pll_p");
+	if (IS_ERR(pll_p_clk))
+		return PTR_ERR(pll_p_clk);
+
+	emc_clk = clk_get_sys("cpu", "emc");
+	if (IS_ERR(emc_clk)) {
+		clk_put(cpu_clk);
+		return PTR_ERR(emc_clk);
+	}
+
+	return cpufreq_register_driver(&tegra_cpufreq_driver);
+}
+
+static void __exit tegra_cpufreq_exit(void)
+{
+        cpufreq_unregister_driver(&tegra_cpufreq_driver);
+	clk_put(emc_clk);
+	clk_put(cpu_clk);
+}
+
+
+MODULE_AUTHOR("Colin Cross <ccross@android.com>");
+MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
+MODULE_LICENSE("GPL");
+module_init(tegra_cpufreq_init);
+module_exit(tegra_cpufreq_exit);