cpufreq: sa11x0: move cpufreq driver to drivers/cpufreq

This patch moves cpufreq driver of ARM based sa11x0 platform to drivers/cpufreq.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 247 insertions, 0 deletions

diff --git a/drivers/cpufreq/sa1100-cpufreq.c b/drivers/cpufreq/sa1100-cpufreq.c
new file mode 100644
index 000000000000..cff18e87ca58
--- /dev/null
+++ b/drivers/cpufreq/sa1100-cpufreq.c
@@ -0,0 +1,247 @@
+/*
+ * cpu-sa1100.c: clock scaling for the SA1100
+ *
+ * Copyright (C) 2000 2001, The Delft University of Technology
+ *
+ * Authors:
+ * - Johan Pouwelse (J.A.Pouwelse@its.tudelft.nl): initial version
+ * - Erik Mouw (J.A.K.Mouw@its.tudelft.nl):
+ *   - major rewrite for linux-2.3.99
+ *   - rewritten for the more generic power management scheme in
+ *     linux-2.4.5-rmk1
+ *
+ * This software has been developed while working on the LART
+ * computing board (http://www.lartmaker.nl/), which is
+ * sponsored by the Mobile Multi-media Communications
+ * (http://www.mobimedia.org/) and Ubiquitous Communications
+ * (http://www.ubicom.tudelft.nl/) projects.
+ *
+ * The authors can be reached at:
+ *
+ *  Erik Mouw
+ *  Information and Communication Theory Group
+ *  Faculty of Information Technology and Systems
+ *  Delft University of Technology
+ *  P.O. Box 5031
+ *  2600 GA Delft
+ *  The Netherlands
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *
+ * Theory of operations
+ * ====================
+ *
+ * Clock scaling can be used to lower the power consumption of the CPU
+ * core. This will give you a somewhat longer running time.
+ *
+ * The SA-1100 has a single register to change the core clock speed:
+ *
+ *   PPCR      0x90020014    PLL config
+ *
+ * However, the DRAM timings are closely related to the core clock
+ * speed, so we need to change these, too. The used registers are:
+ *
+ *   MDCNFG    0xA0000000    DRAM config
+ *   MDCAS0    0xA0000004    Access waveform
+ *   MDCAS1    0xA0000008    Access waveform
+ *   MDCAS2    0xA000000C    Access waveform
+ *
+ * Care must be taken to change the DRAM parameters the correct way,
+ * because otherwise the DRAM becomes unusable and the kernel will
+ * crash.
+ *
+ * The simple solution to avoid a kernel crash is to put the actual
+ * clock change in ROM and jump to that code from the kernel. The main
+ * disadvantage is that the ROM has to be modified, which is not
+ * possible on all SA-1100 platforms. Another disadvantage is that
+ * jumping to ROM makes clock switching unnecessary complicated.
+ *
+ * The idea behind this driver is that the memory configuration can be
+ * changed while running from DRAM (even with interrupts turned on!)
+ * as long as all re-configuration steps yield a valid DRAM
+ * configuration. The advantages are clear: it will run on all SA-1100
+ * platforms, and the code is very simple.
+ *
+ * If you really want to understand what is going on in
+ * sa1100_update_dram_timings(), you'll have to read sections 8.2,
+ * 9.5.7.3, and 10.2 from the "Intel StrongARM SA-1100 Microprocessor
+ * Developers Manual" (available for free from Intel).
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/io.h>
+
+#include <asm/cputype.h>
+
+#include <mach/generic.h>
+#include <mach/hardware.h>
+
+struct sa1100_dram_regs {
+	int speed;
+	u32 mdcnfg;
+	u32 mdcas0;
+	u32 mdcas1;
+	u32 mdcas2;
+};
+
+
+static struct cpufreq_driver sa1100_driver;
+
+static struct sa1100_dram_regs sa1100_dram_settings[] = {
+	/*speed,     mdcnfg,     mdcas0,     mdcas1,     mdcas2,   clock freq */
+	{ 59000, 0x00dc88a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/*  59.0 MHz */
+	{ 73700, 0x011490a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/*  73.7 MHz */
+	{ 88500, 0x014e90a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/*  88.5 MHz */
+	{103200, 0x01889923, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 103.2 MHz */
+	{118000, 0x01c29923, 0x9999998f, 0xfffffff9, 0xffffffff},/* 118.0 MHz */
+	{132700, 0x01fb2123, 0x9999998f, 0xfffffff9, 0xffffffff},/* 132.7 MHz */
+	{147500, 0x02352123, 0x3333330f, 0xfffffff3, 0xffffffff},/* 147.5 MHz */
+	{162200, 0x026b29a3, 0x38e38e1f, 0xfff8e38e, 0xffffffff},/* 162.2 MHz */
+	{176900, 0x02a329a3, 0x71c71c1f, 0xfff1c71c, 0xffffffff},/* 176.9 MHz */
+	{191700, 0x02dd31a3, 0xe38e383f, 0xffe38e38, 0xffffffff},/* 191.7 MHz */
+	{206400, 0x03153223, 0xc71c703f, 0xffc71c71, 0xffffffff},/* 206.4 MHz */
+	{221200, 0x034fba23, 0xc71c703f, 0xffc71c71, 0xffffffff},/* 221.2 MHz */
+	{235900, 0x03853a23, 0xe1e1e07f, 0xe1e1e1e1, 0xffffffe1},/* 235.9 MHz */
+	{250700, 0x03bf3aa3, 0xc3c3c07f, 0xc3c3c3c3, 0xffffffc3},/* 250.7 MHz */
+	{265400, 0x03f7c2a3, 0xc3c3c07f, 0xc3c3c3c3, 0xffffffc3},/* 265.4 MHz */
+	{280200, 0x0431c2a3, 0x878780ff, 0x87878787, 0xffffff87},/* 280.2 MHz */
+	{ 0, 0, 0, 0, 0 } /* last entry */
+};
+
+static void sa1100_update_dram_timings(int current_speed, int new_speed)
+{
+	struct sa1100_dram_regs *settings = sa1100_dram_settings;
+
+	/* find speed */
+	while (settings->speed != 0) {
+		if (new_speed == settings->speed)
+			break;
+
+		settings++;
+	}
+
+	if (settings->speed == 0) {
+		panic("%s: couldn't find dram setting for speed %d\n",
+		      __func__, new_speed);
+	}
+
+	/* No risk, no fun: run with interrupts on! */
+	if (new_speed > current_speed) {
+		/* We're going FASTER, so first relax the memory
+		 * timings before changing the core frequency
+		 */
+
+		/* Half the memory access clock */
+		MDCNFG |= MDCNFG_CDB2;
+
+		/* The order of these statements IS important, keep 8
+		 * pulses!!
+		 */
+		MDCAS2 = settings->mdcas2;
+		MDCAS1 = settings->mdcas1;
+		MDCAS0 = settings->mdcas0;
+		MDCNFG = settings->mdcnfg;
+	} else {
+		/* We're going SLOWER: first decrease the core
+		 * frequency and then tighten the memory settings.
+		 */
+
+		/* Half the memory access clock */
+		MDCNFG |= MDCNFG_CDB2;
+
+		/* The order of these statements IS important, keep 8
+		 * pulses!!
+		 */
+		MDCAS0 = settings->mdcas0;
+		MDCAS1 = settings->mdcas1;
+		MDCAS2 = settings->mdcas2;
+		MDCNFG = settings->mdcnfg;
+	}
+}
+
+static int sa1100_target(struct cpufreq_policy *policy,
+			 unsigned int target_freq,
+			 unsigned int relation)
+{
+	unsigned int cur = sa11x0_getspeed(0);
+	unsigned int new_ppcr;
+	struct cpufreq_freqs freqs;
+
+	new_ppcr = sa11x0_freq_to_ppcr(target_freq);
+	switch (relation) {
+	case CPUFREQ_RELATION_L:
+		if (sa11x0_ppcr_to_freq(new_ppcr) > policy->max)
+			new_ppcr--;
+		break;
+	case CPUFREQ_RELATION_H:
+		if ((sa11x0_ppcr_to_freq(new_ppcr) > target_freq) &&
+		    (sa11x0_ppcr_to_freq(new_ppcr - 1) >= policy->min))
+			new_ppcr--;
+		break;
+	}
+
+	freqs.old = cur;
+	freqs.new = sa11x0_ppcr_to_freq(new_ppcr);
+
+	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
+
+	if (freqs.new > cur)
+		sa1100_update_dram_timings(cur, freqs.new);
+
+	PPCR = new_ppcr;
+
+	if (freqs.new < cur)
+		sa1100_update_dram_timings(cur, freqs.new);
+
+	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
+
+	return 0;
+}
+
+static int __init sa1100_cpu_init(struct cpufreq_policy *policy)
+{
+	if (policy->cpu != 0)
+		return -EINVAL;
+	policy->cur = policy->min = policy->max = sa11x0_getspeed(0);
+	policy->cpuinfo.min_freq = 59000;
+	policy->cpuinfo.max_freq = 287000;
+	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
+	return 0;
+}
+
+static struct cpufreq_driver sa1100_driver __refdata = {
+	.flags		= CPUFREQ_STICKY,
+	.verify		= sa11x0_verify_speed,
+	.target		= sa1100_target,
+	.get		= sa11x0_getspeed,
+	.init		= sa1100_cpu_init,
+	.name		= "sa1100",
+};
+
+static int __init sa1100_dram_init(void)
+{
+	if (cpu_is_sa1100())
+		return cpufreq_register_driver(&sa1100_driver);
+	else
+		return -ENODEV;
+}
+
+arch_initcall(sa1100_dram_init);