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From:   Markus Schneider-Pargmann <msp@baylibre.com>
To:     Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Weiyi Lu <weiyi.lu@mediatek.com>
Cc:     Fabien Parent <parent.f@gmail.com>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        Alexandre Bailon <abailon@baylibre.com>,
        Fabien Parent <fparent@baylibre.com>,
        Markus Schneider-Pargmann <msp@baylibre.com>
Subject: [PATCH v2 3/4] soc: mediatek: add support of MTK_SCPD_STRICT_BUSP cap
Date:   Mon, 25 Jul 2022 10:18:52 +0200
Message-Id: <20220725081853.1636444-4-msp@baylibre.com>
In-Reply-To: <20220725081853.1636444-1-msp@baylibre.com>
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From: Alexandre Bailon <abailon@baylibre.com>

This adds support for MTK_SCPD_STRICT_BUSP capability. It is a strict
bus protection policy that requires the bus protection to be disabled
before accessing the bus.
This is required by the mt8365, for the MM power domain.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
Signed-off-by: Fabien Parent <fparent@baylibre.com>
Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---

Notes:
    Changes in v2:
    - Fixup error handling path.

 drivers/soc/mediatek/mtk-pm-domains.c | 29 +++++++++++++++++++++++----
 drivers/soc/mediatek/mtk-pm-domains.h |  1 +
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/soc/mediatek/mtk-pm-domains.c b/drivers/soc/mediatek/mtk-pm-domains.c
index d0eae2227813..94ca8981f45e 100644
--- a/drivers/soc/mediatek/mtk-pm-domains.c
+++ b/drivers/soc/mediatek/mtk-pm-domains.c
@@ -240,6 +240,7 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
 	struct scpsys *scpsys = pd->scpsys;
 	bool tmp;
 	int ret;
+	bool strict_busprotect;
 
 	ret = scpsys_regulator_enable(pd->supply);
 	if (ret)
@@ -263,9 +264,18 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
 	regmap_clear_bits(scpsys->base, pd->data->ctl_offs, PWR_ISO_BIT);
 	regmap_set_bits(scpsys->base, pd->data->ctl_offs, PWR_RST_B_BIT);
 
-	ret = clk_bulk_prepare_enable(pd->num_subsys_clks, pd->subsys_clks);
-	if (ret)
-		goto err_pwr_ack;
+	/*
+	 * In few Mediatek platforms(e.g. MT6779), the bus protect policy is
+	 * stricter, which leads to bus protect release must be prior to bus
+	 * access.
+	 */
+	strict_busprotect = MTK_SCPD_CAPS(pd, MTK_SCPD_STRICT_BUSP);
+	if (!strict_busprotect) {
+		ret = clk_bulk_prepare_enable(pd->num_subsys_clks,
+					      pd->subsys_clks);
+		if (ret)
+			goto err_pwr_ack;
+	}
 
 	ret = scpsys_sram_enable(pd);
 	if (ret < 0)
@@ -275,12 +285,23 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
 	if (ret < 0)
 		goto err_disable_sram;
 
+	if (strict_busprotect) {
+		ret = clk_bulk_prepare_enable(pd->num_subsys_clks,
+					      pd->subsys_clks);
+		if (ret)
+			goto err_enable_bus_protect;
+	}
+
 	return 0;
 
+err_enable_bus_protect:
+	scpsys_bus_protect_enable(pd);
 err_disable_sram:
 	scpsys_sram_disable(pd);
 err_disable_subsys_clks:
-	clk_bulk_disable_unprepare(pd->num_subsys_clks, pd->subsys_clks);
+	if (!strict_busprotect)
+		clk_bulk_disable_unprepare(pd->num_subsys_clks,
+					   pd->subsys_clks);
 err_pwr_ack:
 	clk_bulk_disable_unprepare(pd->num_clks, pd->clks);
 err_reg:
diff --git a/drivers/soc/mediatek/mtk-pm-domains.h b/drivers/soc/mediatek/mtk-pm-domains.h
index e788d6bdde9d..a50cfb926d22 100644
--- a/drivers/soc/mediatek/mtk-pm-domains.h
+++ b/drivers/soc/mediatek/mtk-pm-domains.h
@@ -8,6 +8,7 @@
 #define MTK_SCPD_SRAM_ISO		BIT(2)
 #define MTK_SCPD_KEEP_DEFAULT_OFF	BIT(3)
 #define MTK_SCPD_DOMAIN_SUPPLY		BIT(4)
+#define MTK_SCPD_STRICT_BUSP		BIT(5)
 #define MTK_SCPD_CAPS(_scpd, _x)	((_scpd)->data->caps & (_x))
 
 #define SPM_VDE_PWR_CON			0x0210
-- 
2.36.1