1 files changed, 320 insertions, 25 deletions

diff --git a/drivers/memory/samsung/exynos5422-dmc.c b/drivers/memory/samsung/exynos5422-dmc.c
index 0fe5f2186139..47dbf6d1789f 100644
--- a/drivers/memory/samsung/exynos5422-dmc.c
+++ b/drivers/memory/samsung/exynos5422-dmc.c
@@ -8,6 +8,7 @@
 #include <linux/devfreq.h>
 #include <linux/devfreq-event.h>
 #include <linux/device.h>
+#include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
@@ -35,6 +36,61 @@
 #define USE_BPLL_TIMINGS			(0)
 #define EXYNOS5_AREF_NORMAL			(0x2e)
 
+#define DREX_PPCCLKCON		(0x0130)
+#define DREX_PEREV2CONFIG	(0x013c)
+#define DREX_PMNC_PPC		(0xE000)
+#define DREX_CNTENS_PPC		(0xE010)
+#define DREX_CNTENC_PPC		(0xE020)
+#define DREX_INTENS_PPC		(0xE030)
+#define DREX_INTENC_PPC		(0xE040)
+#define DREX_FLAG_PPC		(0xE050)
+#define DREX_PMCNT2_PPC		(0xE130)
+
+/*
+ * A value for register DREX_PMNC_PPC which should be written to reset
+ * the cycle counter CCNT (a reference wall clock). It sets zero to the
+ * CCNT counter.
+ */
+#define CC_RESET		BIT(2)
+
+/*
+ * A value for register DREX_PMNC_PPC which does the reset of all performance
+ * counters to zero.
+ */
+#define PPC_COUNTER_RESET	BIT(1)
+
+/*
+ * Enables all configured counters (including cycle counter). The value should
+ * be written to the register DREX_PMNC_PPC.
+ */
+#define PPC_ENABLE		BIT(0)
+
+/* A value for register DREX_PPCCLKCON which enables performance events clock.
+ * Must be written before first access to the performance counters register
+ * set, otherwise it could crash.
+ */
+#define PEREV_CLK_EN		BIT(0)
+
+/*
+ * Values which are used to enable counters, interrupts or configure flags of
+ * the performance counters. They configure counter 2 and cycle counter.
+ */
+#define PERF_CNT2		BIT(2)
+#define PERF_CCNT		BIT(31)
+
+/*
+ * Performance event types which are used for setting the preferred event
+ * to track in the counters.
+ * There is a set of different types, the values are from range 0 to 0x6f.
+ * These settings should be written to the configuration register which manages
+ * the type of the event (register DREX_PEREV2CONFIG).
+ */
+#define READ_TRANSFER_CH0	(0x6d)
+#define READ_TRANSFER_CH1	(0x6f)
+
+#define PERF_COUNTER_START_VALUE 0xff000000
+#define PERF_EVENT_UP_DOWN_THRESHOLD 900000000ULL
+
 /**
  * struct dmc_opp_table - Operating level desciption
  *
@@ -85,6 +141,10 @@ struct exynos5_dmc {
 	struct clk *mout_mx_mspll_ccore_phy;
 	struct devfreq_event_dev **counter;
 	int num_counters;
+	u64 last_overflow_ts[2];
+	unsigned long load;
+	unsigned long total;
+	bool in_irq_mode;
 };
 
 #define TIMING_FIELD(t_name, t_bit_beg, t_bit_end) \
@@ -654,6 +714,173 @@ static int exynos5_counters_get(struct exynos5_dmc *dmc,
 }
 
 /**
+ * exynos5_dmc_start_perf_events() - Setup and start performance event counters
+ * @dmc:	device for which the counters are going to be checked
+ * @beg_value:	initial value for the counter
+ *
+ * Function which enables needed counters, interrupts and sets initial values
+ * then starts the counters.
+ */
+static void exynos5_dmc_start_perf_events(struct exynos5_dmc *dmc,
+					  u32 beg_value)
+{
+	/* Enable interrupts for counter 2 */
+	writel(PERF_CNT2, dmc->base_drexi0 + DREX_INTENS_PPC);
+	writel(PERF_CNT2, dmc->base_drexi1 + DREX_INTENS_PPC);
+
+	/* Enable counter 2 and CCNT  */
+	writel(PERF_CNT2 | PERF_CCNT, dmc->base_drexi0 + DREX_CNTENS_PPC);
+	writel(PERF_CNT2 | PERF_CCNT, dmc->base_drexi1 + DREX_CNTENS_PPC);
+
+	/* Clear overflow flag for all counters */
+	writel(PERF_CNT2 | PERF_CCNT, dmc->base_drexi0 + DREX_FLAG_PPC);
+	writel(PERF_CNT2 | PERF_CCNT, dmc->base_drexi1 + DREX_FLAG_PPC);
+
+	/* Reset all counters */
+	writel(CC_RESET | PPC_COUNTER_RESET, dmc->base_drexi0 + DREX_PMNC_PPC);
+	writel(CC_RESET | PPC_COUNTER_RESET, dmc->base_drexi1 + DREX_PMNC_PPC);
+
+	/*
+	 * Set start value for the counters, the number of samples that
+	 * will be gathered is calculated as: 0xffffffff - beg_value
+	 */
+	writel(beg_value, dmc->base_drexi0 + DREX_PMCNT2_PPC);
+	writel(beg_value, dmc->base_drexi1 + DREX_PMCNT2_PPC);
+
+	/* Start all counters */
+	writel(PPC_ENABLE, dmc->base_drexi0 + DREX_PMNC_PPC);
+	writel(PPC_ENABLE, dmc->base_drexi1 + DREX_PMNC_PPC);
+}
+
+/**
+ * exynos5_dmc_perf_events_calc() - Calculate utilization
+ * @dmc:	device for which the counters are going to be checked
+ * @diff_ts:	time between last interrupt and current one
+ *
+ * Function which calculates needed utilization for the devfreq governor.
+ * It prepares values for 'busy_time' and 'total_time' based on elapsed time
+ * between interrupts, which approximates utilization.
+ */
+static void exynos5_dmc_perf_events_calc(struct exynos5_dmc *dmc, u64 diff_ts)
+{
+	/*
+	 * This is a simple algorithm for managing traffic on DMC.
+	 * When there is almost no load the counters overflow every 4s,
+	 * no mater the DMC frequency.
+	 * The high load might be approximated using linear function.
+	 * Knowing that, simple calculation can provide 'busy_time' and
+	 * 'total_time' to the devfreq governor which picks up target
+	 * frequency.
+	 * We want a fast ramp up and slow decay in frequency change function.
+	 */
+	if (diff_ts < PERF_EVENT_UP_DOWN_THRESHOLD) {
+		/*
+		 * Set higher utilization for the simple_ondemand governor.
+		 * The governor should increase the frequency of the DMC.
+		 */
+		dmc->load = 70;
+		dmc->total = 100;
+	} else {
+		/*
+		 * Set low utilization for the simple_ondemand governor.
+		 * The governor should decrease the frequency of the DMC.
+		 */
+		dmc->load = 35;
+		dmc->total = 100;
+	}
+
+	dev_dbg(dmc->dev, "diff_ts=%llu\n", diff_ts);
+}
+
+/**
+ * exynos5_dmc_perf_events_check() - Checks the status of the counters
+ * @dmc:	device for which the counters are going to be checked
+ *
+ * Function which is called from threaded IRQ to check the counters state
+ * and to call approximation for the needed utilization.
+ */
+static void exynos5_dmc_perf_events_check(struct exynos5_dmc *dmc)
+{
+	u32 val;
+	u64 diff_ts, ts;
+
+	ts = ktime_get_ns();
+
+	/* Stop all counters */
+	writel(0, dmc->base_drexi0 + DREX_PMNC_PPC);
+	writel(0, dmc->base_drexi1 + DREX_PMNC_PPC);
+
+	/* Check the source in interrupt flag registers (which channel) */
+	val = readl(dmc->base_drexi0 + DREX_FLAG_PPC);
+	if (val) {
+		diff_ts = ts - dmc->last_overflow_ts[0];
+		dmc->last_overflow_ts[0] = ts;
+		dev_dbg(dmc->dev, "drex0 0xE050 val= 0x%08x\n",  val);
+	} else {
+		val = readl(dmc->base_drexi1 + DREX_FLAG_PPC);
+		diff_ts = ts - dmc->last_overflow_ts[1];
+		dmc->last_overflow_ts[1] = ts;
+		dev_dbg(dmc->dev, "drex1 0xE050 val= 0x%08x\n",  val);
+	}
+
+	exynos5_dmc_perf_events_calc(dmc, diff_ts);
+
+	exynos5_dmc_start_perf_events(dmc, PERF_COUNTER_START_VALUE);
+}
+
+/**
+ * exynos5_dmc_enable_perf_events() - Enable performance events
+ * @dmc:	device for which the counters are going to be checked
+ *
+ * Function which is setup needed environment and enables counters.
+ */
+static void exynos5_dmc_enable_perf_events(struct exynos5_dmc *dmc)
+{
+	u64 ts;
+
+	/* Enable Performance Event Clock */
+	writel(PEREV_CLK_EN, dmc->base_drexi0 + DREX_PPCCLKCON);
+	writel(PEREV_CLK_EN, dmc->base_drexi1 + DREX_PPCCLKCON);
+
+	/* Select read transfers as performance event2 */
+	writel(READ_TRANSFER_CH0, dmc->base_drexi0 + DREX_PEREV2CONFIG);
+	writel(READ_TRANSFER_CH1, dmc->base_drexi1 + DREX_PEREV2CONFIG);
+
+	ts = ktime_get_ns();
+	dmc->last_overflow_ts[0] = ts;
+	dmc->last_overflow_ts[1] = ts;
+
+	/* Devfreq shouldn't be faster than initialization, play safe though. */
+	dmc->load = 99;
+	dmc->total = 100;
+}
+
+/**
+ * exynos5_dmc_disable_perf_events() - Disable performance events
+ * @dmc:	device for which the counters are going to be checked
+ *
+ * Function which stops, disables performance event counters and interrupts.
+ */
+static void exynos5_dmc_disable_perf_events(struct exynos5_dmc *dmc)
+{
+	/* Stop all counters */
+	writel(0, dmc->base_drexi0 + DREX_PMNC_PPC);
+	writel(0, dmc->base_drexi1 + DREX_PMNC_PPC);
+
+	/* Disable interrupts for counter 2 */
+	writel(PERF_CNT2, dmc->base_drexi0 + DREX_INTENC_PPC);
+	writel(PERF_CNT2, dmc->base_drexi1 + DREX_INTENC_PPC);
+
+	/* Disable counter 2 and CCNT  */
+	writel(PERF_CNT2 | PERF_CCNT, dmc->base_drexi0 + DREX_CNTENC_PPC);
+	writel(PERF_CNT2 | PERF_CCNT, dmc->base_drexi1 + DREX_CNTENC_PPC);
+
+	/* Clear overflow flag for all counters */
+	writel(PERF_CNT2 | PERF_CCNT, dmc->base_drexi0 + DREX_FLAG_PPC);
+	writel(PERF_CNT2 | PERF_CCNT, dmc->base_drexi1 + DREX_FLAG_PPC);
+}
+
+/**
  * exynos5_dmc_get_status() - Read current DMC performance statistics.
  * @dev:	device for which the statistics are requested
  * @stat:	structure which has statistic fields
@@ -669,18 +896,24 @@ static int exynos5_dmc_get_status(struct device *dev,
 	unsigned long load, total;
 	int ret;
 
-	ret = exynos5_counters_get(dmc, &load, &total);
-	if (ret < 0)
-		return -EINVAL;
+	if (dmc->in_irq_mode) {
+		stat->current_frequency = dmc->curr_rate;
+		stat->busy_time = dmc->load;
+		stat->total_time = dmc->total;
+	} else {
+		ret = exynos5_counters_get(dmc, &load, &total);
+		if (ret < 0)
+			return -EINVAL;
 
-	/* To protect from overflow in calculation ratios, divide by 1024 */
-	stat->busy_time = load >> 10;
-	stat->total_time = total >> 10;
+		/* To protect from overflow, divide by 1024 */
+		stat->busy_time = load >> 10;
+		stat->total_time = total >> 10;
 
-	ret = exynos5_counters_set_event(dmc);
-	if (ret < 0) {
-		dev_err(dev, "could not set event counter\n");
-		return ret;
+		ret = exynos5_counters_set_event(dmc);
+		if (ret < 0) {
+			dev_err(dev, "could not set event counter\n");
+			return ret;
+		}
 	}
 
 	return 0;
@@ -712,7 +945,6 @@ static int exynos5_dmc_get_cur_freq(struct device *dev, unsigned long *freq)
  * It provides to the devfreq framework needed functions and polling period.
  */
 static struct devfreq_dev_profile exynos5_dmc_df_profile = {
-	.polling_ms = 500,
 	.target = exynos5_dmc_target,
 	.get_dev_status = exynos5_dmc_get_status,
 	.get_cur_freq = exynos5_dmc_get_cur_freq,
@@ -1108,6 +1340,24 @@ static inline int exynos5_dmc_set_pause_on_switching(struct exynos5_dmc *dmc)
 	return 0;
 }
 
+static irqreturn_t dmc_irq_thread(int irq, void *priv)
+{
+	int res;
+	struct exynos5_dmc *dmc = priv;
+
+	mutex_lock(&dmc->df->lock);
+
+	exynos5_dmc_perf_events_check(dmc);
+
+	res = update_devfreq(dmc->df);
+	if (res)
+		dev_warn(dmc->dev, "devfreq failed with %d\n", res);
+
+	mutex_unlock(&dmc->df->lock);
+
+	return IRQ_HANDLED;
+}
+
 /**
  * exynos5_dmc_probe() - Probe function for the DMC driver
  * @pdev:	platform device for which the driver is going to be initialized
@@ -1125,6 +1375,7 @@ static int exynos5_dmc_probe(struct platform_device *pdev)
 	struct device_node *np = dev->of_node;
 	struct exynos5_dmc *dmc;
 	struct resource *res;
+	int irq[2];
 
 	dmc = devm_kzalloc(dev, sizeof(*dmc), GFP_KERNEL);
 	if (!dmc)
@@ -1172,24 +1423,59 @@ static int exynos5_dmc_probe(struct platform_device *pdev)
 		goto remove_clocks;
 	}
 
-	ret = exynos5_performance_counters_init(dmc);
+	ret = exynos5_dmc_set_pause_on_switching(dmc);
 	if (ret) {
-		dev_warn(dev, "couldn't probe performance counters\n");
+		dev_warn(dev, "couldn't get access to PAUSE register\n");
 		goto remove_clocks;
 	}
 
-	ret = exynos5_dmc_set_pause_on_switching(dmc);
-	if (ret) {
-		dev_warn(dev, "couldn't get access to PAUSE register\n");
-		goto err_devfreq_add;
+	/* There is two modes in which the driver works: polling or IRQ */
+	irq[0] = platform_get_irq_byname(pdev, "drex_0");
+	irq[1] = platform_get_irq_byname(pdev, "drex_1");
+	if (irq[0] > 0 && irq[1] > 0) {
+		ret = devm_request_threaded_irq(dev, irq[0], NULL,
+						dmc_irq_thread, IRQF_ONESHOT,
+						dev_name(dev), dmc);
+		if (ret) {
+			dev_err(dev, "couldn't grab IRQ\n");
+			goto remove_clocks;
+		}
+
+		ret = devm_request_threaded_irq(dev, irq[1], NULL,
+						dmc_irq_thread, IRQF_ONESHOT,
+						dev_name(dev), dmc);
+		if (ret) {
+			dev_err(dev, "couldn't grab IRQ\n");
+			goto remove_clocks;
+		}
+
+		/*
+		 * Setup default thresholds for the devfreq governor.
+		 * The values are chosen based on experiments.
+		 */
+		dmc->gov_data.upthreshold = 55;
+		dmc->gov_data.downdifferential = 5;
+
+		exynos5_dmc_enable_perf_events(dmc);
+
+		dmc->in_irq_mode = 1;
+	} else {
+		ret = exynos5_performance_counters_init(dmc);
+		if (ret) {
+			dev_warn(dev, "couldn't probe performance counters\n");
+			goto remove_clocks;
+		}
+
+		/*
+		 * Setup default thresholds for the devfreq governor.
+		 * The values are chosen based on experiments.
+		 */
+		dmc->gov_data.upthreshold = 30;
+		dmc->gov_data.downdifferential = 5;
+
+		exynos5_dmc_df_profile.polling_ms = 500;
 	}
 
-	/*
-	 * Setup default thresholds for the devfreq governor.
-	 * The values are chosen based on experiments.
-	 */
-	dmc->gov_data.upthreshold = 30;
-	dmc->gov_data.downdifferential = 5;
 
 	dmc->df = devm_devfreq_add_device(dev, &exynos5_dmc_df_profile,
 					  DEVFREQ_GOV_SIMPLE_ONDEMAND,
@@ -1200,12 +1486,18 @@ static int exynos5_dmc_probe(struct platform_device *pdev)
 		goto err_devfreq_add;
 	}
 
+	if (dmc->in_irq_mode)
+		exynos5_dmc_start_perf_events(dmc, PERF_COUNTER_START_VALUE);
+
 	dev_info(dev, "DMC initialized\n");
 
 	return 0;
 
 err_devfreq_add:
-	exynos5_counters_disable_edev(dmc);
+	if (dmc->in_irq_mode)
+		exynos5_dmc_disable_perf_events(dmc);
+	else
+		exynos5_counters_disable_edev(dmc);
 remove_clocks:
 	clk_disable_unprepare(dmc->mout_bpll);
 	clk_disable_unprepare(dmc->fout_bpll);
@@ -1225,7 +1517,10 @@ static int exynos5_dmc_remove(struct platform_device *pdev)
 {
 	struct exynos5_dmc *dmc = dev_get_drvdata(&pdev->dev);
 
-	exynos5_counters_disable_edev(dmc);
+	if (dmc->in_irq_mode)
+		exynos5_dmc_disable_perf_events(dmc);
+	else
+		exynos5_counters_disable_edev(dmc);
 
 	clk_disable_unprepare(dmc->mout_bpll);
 	clk_disable_unprepare(dmc->fout_bpll);