soc: qcom: qcom_stats: Add QMP support for syncing ddr stats

Recent SoCs (SM8450 onwards) require QMP command to be sent before reading
ddr stats. The duration field of ddr stats will get populated only if QMP
command is sent.

Add support to send ddr stats freqsync QMP command.

Signed-off-by: Maulik Shah <[e-mail]>
Reviewed-by: Dmitry Baryshkov <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bjorn Andersson <[e-mail]>

drivers/soc/qcom/qcom_stats.c

···
 #include <linux/platform_device.h>
 #include <linux/seq_file.h>
 
+#include <linux/soc/qcom/qcom_aoss.h>
 #include <linux/soc/qcom/smem.h>
 #include <clocksource/arm_arch_timer.h>
 
···
 #define DDR_STATS_LPM_NAME(data)	FIELD_GET(GENMASK(7, 0), data)
 #define DDR_STATS_TYPE(data)		FIELD_GET(GENMASK(15, 8), data)
 #define DDR_STATS_FREQ(data)		FIELD_GET(GENMASK(31, 16), data)
+
+static struct qmp *qcom_stats_qmp;
 
 struct subsystem_data {
 	const char *name;
···
 	struct ddr_stats_entry data[DDR_STATS_MAX_NUM_MODES];
 	void __iomem *reg = (void __iomem *)s->private;
 	u32 entry_count;
-	int i;
+	int i, ret;
 
 	entry_count = readl_relaxed(reg + DDR_STATS_NUM_MODES_ADDR);
 	if (entry_count > DDR_STATS_MAX_NUM_MODES)
 		return -EINVAL;
+
+	if (qcom_stats_qmp) {
+		/*
+		 * Recent SoCs (SM8450 onwards) do not have duration field
+		 * populated from boot up onwards for both DDR LPM Stats
+		 * and DDR Frequency Stats.
+		 *
+		 * Send QMP message to Always on processor which will
+		 * populate duration field into MSG RAM area.
+		 *
+		 * Sent every time to read latest data.
+		 */
+		ret = qmp_send(qcom_stats_qmp, "{class: ddr, action: freqsync}");
+		if (ret)
+			return ret;
+	}
 
 	reg += DDR_STATS_ENTRY_START_ADDR;
 	memcpy_fromio(data, reg, sizeof(struct ddr_stats_entry) * entry_count);
···
 
 	for (i = 0; i < config->num_records; i++)
 		d[i].appended_stats_avail = config->appended_stats_avail;
+	/*
+	 * QMP is used for DDR stats syncing to MSG RAM for recent SoCs (SM8450 onwards).
+	 * The prior SoCs do not need QMP handle as the required stats are already present
+	 * in MSG RAM, provided the DDR_STATS_MAGIC_KEY matches.
+	 */
+	qcom_stats_qmp = qmp_get(&pdev->dev);
+	if (IS_ERR(qcom_stats_qmp)) {
+		/* We ignore error if QMP is not defined/needed */
+		if (!of_property_present(pdev->dev.of_node, "qcom,qmp"))
+			qcom_stats_qmp = NULL;
+		else if (PTR_ERR(qcom_stats_qmp) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		else
+			return PTR_ERR(qcom_stats_qmp);
+	}
 
 	root = debugfs_create_dir("qcom_stats", NULL);