ARM: OSIRIS: DVS (Dynamic Voltage Scaling) supoort.

Add a driver to provide DVS for the Simtec Osiris module to reduce
the power consumption whilst idling.

The DVS driver alters the voltage supplied to the ARM core depending
on the frequency it is running at. The driver itself does not do any
of the frequency alteration, which is left up to the cpufreq driver.

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Signed-off-by: Simtec Linux Team <linux@simtec.co.uk>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

1 files changed, 194 insertions, 0 deletions

diff --git a/arch/arm/mach-s3c2440/mach-osiris-dvs.c b/arch/arm/mach-s3c2440/mach-osiris-dvs.c
new file mode 100644
index 000000000000..ad2792dfbee1
--- /dev/null
+++ b/arch/arm/mach-s3c2440/mach-osiris-dvs.c
@@ -0,0 +1,194 @@
+/* linux/arch/arm/mach-s3c2440/mach-osiris-dvs.c
+ *
+ * Copyright (c) 2009 Simtec Electronics
+ *      http://armlinux.simtec.co.uk/
+ *      Ben Dooks <ben@simtec.co.uk>
+ *
+ * Simtec Osiris Dynamic Voltage Scaling support.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/cpufreq.h>
+#include <linux/gpio.h>
+
+#include <linux/i2c/tps65010.h>
+
+#include <plat/cpu-freq.h>
+
+#define OSIRIS_GPIO_DVS S3C2410_GPB(5)
+
+static bool dvs_en;
+
+static void osiris_dvs_tps_setdvs(bool on)
+{
+        unsigned vregs1 = 0, vdcdc2 = 0;
+
+        if (!on) {
+                vdcdc2 = TPS_VCORE_DISCH | TPS_LP_COREOFF;
+                vregs1 = TPS_LDO1_OFF;  /* turn off in low-power mode */
+        }
+
+        dvs_en = on;
+        vdcdc2 |= TPS_VCORE_1_3V | TPS_VCORE_LP_1_0V;
+        vregs1 |= TPS_LDO2_ENABLE | TPS_LDO1_ENABLE;
+
+        tps65010_config_vregs1(vregs1);
+        tps65010_config_vdcdc2(vdcdc2);
+}
+
+static bool is_dvs(struct s3c_freq *f)
+{
+        /* at the moment, we assume ARMCLK = HCLK => DVS */
+        return f->armclk == f->hclk;
+}
+
+/* keep track of current state */
+static bool cur_dvs = false;
+
+static int osiris_dvs_notify(struct notifier_block *nb,
+                              unsigned long val, void *data)
+{
+        struct cpufreq_freqs *cf = data;
+        struct s3c_cpufreq_freqs *freqs = to_s3c_cpufreq(cf);
+        bool old_dvs = is_dvs(&freqs->old);
+        bool new_dvs = is_dvs(&freqs->new);
+        int ret = 0;
+
+        if (!dvs_en)
+                return 0;
+
+        printk(KERN_DEBUG "%s: old %ld,%ld new %ld,%ld\n", __func__,
+               freqs->old.armclk, freqs->old.hclk,
+               freqs->new.armclk, freqs->new.hclk);
+
+        switch (val) {
+        case CPUFREQ_PRECHANGE:
+                if (old_dvs & !new_dvs ||
+                    cur_dvs & !new_dvs) {
+                        pr_debug("%s: exiting dvs\n", __func__);
+                        cur_dvs = false;
+                        gpio_set_value(OSIRIS_GPIO_DVS, 1);
+                }
+                break;
+        case CPUFREQ_POSTCHANGE:
+                if (!old_dvs & new_dvs ||
+                    !cur_dvs & new_dvs) {
+                        pr_debug("entering dvs\n");
+                        cur_dvs = true;
+                        gpio_set_value(OSIRIS_GPIO_DVS, 0);
+                }
+                break;
+        }
+
+        return ret;
+}
+
+static struct notifier_block osiris_dvs_nb = {
+        .notifier_call  = osiris_dvs_notify,
+};
+
+static int __devinit osiris_dvs_probe(struct platform_device *pdev)
+{
+        int ret;
+
+        dev_info(&pdev->dev, "initialising\n");
+
+        ret = gpio_request(OSIRIS_GPIO_DVS, "osiris-dvs");
+        if (ret) {
+                dev_err(&pdev->dev, "cannot claim gpio\n");
+                goto err_nogpio;
+        }
+
+        /* start with dvs disabled */
+        gpio_direction_output(OSIRIS_GPIO_DVS, 1);
+
+        ret = cpufreq_register_notifier(&osiris_dvs_nb,
+                                        CPUFREQ_TRANSITION_NOTIFIER);
+        if (ret) {
+                dev_err(&pdev->dev, "failed to register with cpufreq\n");
+                goto err_nofreq;
+        }
+
+        osiris_dvs_tps_setdvs(true);
+
+        return 0;
+
+err_nofreq:
+        gpio_free(OSIRIS_GPIO_DVS);
+
+err_nogpio:
+        return ret;
+}
+
+static int __devexit osiris_dvs_remove(struct platform_device *pdev)
+{
+        dev_info(&pdev->dev, "exiting\n");
+
+        /* disable any current dvs */
+        gpio_set_value(OSIRIS_GPIO_DVS, 1);
+        osiris_dvs_tps_setdvs(false);
+
+        cpufreq_unregister_notifier(&osiris_dvs_nb,
+                                    CPUFREQ_TRANSITION_NOTIFIER);
+
+        gpio_free(OSIRIS_GPIO_DVS);
+
+        return 0;
+}
+
+/* the CONFIG_PM block is so small, it isn't worth actaully compiling it
+ * out if the configuration isn't set. */
+
+static int osiris_dvs_suspend(struct device *dev)
+{
+        gpio_set_value(OSIRIS_GPIO_DVS, 1);
+        osiris_dvs_tps_setdvs(false);
+        cur_dvs = false;
+
+        return 0;
+}
+
+static int osiris_dvs_resume(struct device *dev)
+{
+        osiris_dvs_tps_setdvs(true);
+        return 0;
+}
+
+static const struct dev_pm_ops osiris_dvs_pm = {
+        .suspend        = osiris_dvs_suspend,
+        .resume         = osiris_dvs_resume,
+};
+
+static struct platform_driver osiris_dvs_driver = {
+        .probe          = osiris_dvs_probe,
+        .remove         = __devexit_p(osiris_dvs_remove),
+        .driver         = {
+                .name   = "osiris-dvs",
+                .owner  = THIS_MODULE,
+                .pm     = &osiris_dvs_pm,
+        },
+};
+
+static int __init osiris_dvs_init(void)
+{
+        return platform_driver_register(&osiris_dvs_driver);
+}
+
+static void __exit osiris_dvs_exit(void)
+{
+        platform_driver_unregister(&osiris_dvs_driver);
+}
+
+module_init(osiris_dvs_init);
+module_exit(osiris_dvs_exit);
+
+MODULE_DESCRIPTION("Simtec OSIRIS DVS support");
+MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:osiris-dvs");