memory: mtk-smi: Add sleep ctrl function

Sleep control means that when the larb goes to sleep, we should wait a bit
until all the current commands are finished. Thus, when the larb runtime
suspends, we need to enable this function to wait until all the existed
commands are finished. When the larb resumes, just disable this function.
This function only improves the safety of bus. Add a new flag for this
function. Prepare for mt8186.
Signed-off-by: NAnan Sun <anan.sun@mediatek.com>
Signed-off-by: NYong Wu <yong.wu@mediatek.com>
Reviewed-by: NAngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220113111057.29918-7-yong.wu@mediatek.comSigned-off-by: NKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>

drivers/memory/mtk-smi.c

@@ -8,6 +8,7 @@
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
@@ -32,6 +33,10 @@
 #define SMI_DUMMY			0x444
 
 /* SMI LARB */
+#define SMI_LARB_SLP_CON                0xc
+#define SLP_PROT_EN                     BIT(0)
+#define SLP_PROT_RDY                    BIT(16)
+
 #define SMI_LARB_CMD_THRT_CON		0x24
 #define SMI_LARB_THRT_RD_NU_LMT_MSK	GENMASK(7, 4)
 #define SMI_LARB_THRT_RD_NU_LMT		(5 << 4)
@@ -81,6 +86,7 @@
 
 #define MTK_SMI_FLAG_THRT_UPDATE	BIT(0)
 #define MTK_SMI_FLAG_SW_FLAG		BIT(1)
+#define MTK_SMI_FLAG_SLEEP_CTL		BIT(2)
 #define MTK_SMI_CAPS(flags, _x)		(!!((flags) & (_x)))
 
 struct mtk_smi_reg_pair {
@@ -371,6 +377,26 @@ static const struct of_device_id mtk_smi_larb_of_ids[] = {
 	{}
 };
 
+static int mtk_smi_larb_sleep_ctrl_enable(struct mtk_smi_larb *larb)
+{
+	int ret;
+	u32 tmp;
+
+	writel_relaxed(SLP_PROT_EN, larb->base + SMI_LARB_SLP_CON);
+	ret = readl_poll_timeout_atomic(larb->base + SMI_LARB_SLP_CON,
+					tmp, !!(tmp & SLP_PROT_RDY), 10, 1000);
+	if (ret) {
+		/* TODO: Reset this larb if it fails here. */
+		dev_err(larb->smi.dev, "sleep ctrl is not ready(0x%x).\n", tmp);
+	}
+	return ret;
+}
+
+static void mtk_smi_larb_sleep_ctrl_disable(struct mtk_smi_larb *larb)
+{
+	writel_relaxed(0, larb->base + SMI_LARB_SLP_CON);
+}
+
 static int mtk_smi_device_link_common(struct device *dev, struct device **com_dev)
 {
 	struct platform_device *smi_com_pdev;
@@ -483,6 +509,9 @@ static int __maybe_unused mtk_smi_larb_resume(struct device *dev)
 	if (ret)
 		return ret;
 
+	if (MTK_SMI_CAPS(larb->larb_gen->flags_general, MTK_SMI_FLAG_SLEEP_CTL))
+		mtk_smi_larb_sleep_ctrl_disable(larb);
+
 	/* Configure the basic setting for this larb */
 	larb_gen->config_port(dev);
 
@@ -492,6 +521,13 @@ static int __maybe_unused mtk_smi_larb_resume(struct device *dev)
 static int __maybe_unused mtk_smi_larb_suspend(struct device *dev)
 {
 	struct mtk_smi_larb *larb = dev_get_drvdata(dev);
+	int ret;
+
+	if (MTK_SMI_CAPS(larb->larb_gen->flags_general, MTK_SMI_FLAG_SLEEP_CTL)) {
+		ret = mtk_smi_larb_sleep_ctrl_enable(larb);
+		if (ret)
+			return ret;
+	}
 
 	clk_bulk_disable_unprepare(larb->smi.clk_num, larb->smi.clks);
 	return 0;