[PATCH v1 17/30] mmc: sdhci-tegra: Support OPP and core voltage scaling

[Dmitry Osipenko]

Add OPP and SoC core voltage scaling support to the Tegra SDHCI driver.
This is required for enabling system-wide DVFS on older Tegra SoCs.

Tested-by: Peter Geis <pgwipeout at gmail.com>
Tested-by: Nicolas Chauvet <kwizart at gmail.com>
Signed-off-by: Dmitry Osipenko <digetx at gmail.com>
---
 drivers/mmc/host/Kconfig       |  1 +
 drivers/mmc/host/sdhci-tegra.c | 70 ++++++++++++++++++++++++++++++++--
 2 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 310e546e5898..7d719c81b917 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -293,6 +293,7 @@ config MMC_SDHCI_TEGRA
 	depends on MMC_SDHCI_PLTFM
 	select MMC_SDHCI_IO_ACCESSORS
 	select MMC_CQHCI
+	select PM_OPP
 	help
 	  This selects the Tegra SD/MMC controller. If you have a Tegra
 	  platform with SD or MMC devices, say Y or M here.
diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
index ed12aacb1c73..964709a3ccd6 100644
--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c
@@ -14,6 +14,7 @@
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/pm_opp.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset.h>
@@ -754,10 +755,15 @@ static void tegra_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
+	struct device *dev = mmc_dev(host->mmc);
 	unsigned long host_clk;
 
-	if (!clock)
-		return sdhci_set_clock(host, clock);
+	/* disable clock and then remove OPP performance/voltage vote */
+	if (!clock) {
+		sdhci_set_clock(host, clock);
+		dev_pm_opp_set_rate(dev, clock);
+		return;
+	}
 
 	/*
 	 * In DDR50/52 modes the Tegra SDHCI controllers require the SDHCI
@@ -772,7 +778,7 @@ static void tegra_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
 	 * from clk_get_rate() is used.
 	 */
 	host_clk = tegra_host->ddr_signaling ? clock * 2 : clock;
-	clk_set_rate(pltfm_host->clk, host_clk);
+	dev_pm_opp_set_rate(dev, host_clk);
 	tegra_host->curr_clk_rate = host_clk;
 	if (tegra_host->ddr_signaling)
 		host->max_clk = host_clk;
@@ -1558,6 +1564,60 @@ static int sdhci_tegra_add_host(struct sdhci_host *host)
 	return ret;
 }
 
+static void sdhci_tegra_deinit_opp_table(void *data)
+{
+	struct device *dev = data;
+	struct opp_table *opp_table;
+
+	opp_table = dev_pm_opp_get_opp_table(dev);
+	dev_pm_opp_of_remove_table(dev);
+	dev_pm_opp_put_regulators(opp_table);
+	dev_pm_opp_put_opp_table(opp_table);
+}
+
+static int devm_sdhci_tegra_init_opp_table(struct device *dev)
+{
+	struct opp_table *opp_table;
+	const char *rname = "core";
+	int err;
+
+	/* voltage scaling is optional */
+	if (device_property_present(dev, "core-supply"))
+		opp_table = dev_pm_opp_set_regulators(dev, &rname, 1);
+	else
+		opp_table = dev_pm_opp_get_opp_table(dev);
+
+	if (IS_ERR(opp_table))
+		return dev_err_probe(dev, PTR_ERR(opp_table),
+				    "failed to prepare OPP table\n");
+
+	/*
+	 * OPP table presence is optional and we want the set_rate() of OPP
+	 * API to work similarly to clk_set_rate() if table is missing in a
+	 * device-tree.  The add_table() errors out if OPP is missing in DT.
+	 */
+	if (device_property_present(dev, "operating-points-v2")) {
+		err = dev_pm_opp_of_add_table(dev);
+		if (err) {
+			dev_err(dev, "failed to add OPP table: %d\n", err);
+			goto put_table;
+		}
+	}
+
+	err = devm_add_action(dev, sdhci_tegra_deinit_opp_table, dev);
+	if (err)
+		goto remove_table;
+
+	return 0;
+
+remove_table:
+	dev_pm_opp_of_remove_table(dev);
+put_table:
+	dev_pm_opp_put_regulators(opp_table);
+
+	return err;
+}
+
 static int sdhci_tegra_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *match;
@@ -1621,6 +1681,10 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
 		goto err_power_req;
 	}
 
+	rc = devm_sdhci_tegra_init_opp_table(&pdev->dev);
+	if (rc)
+		goto err_parse_dt;
+
 	/*
 	 * Tegra210 has a separate SDMMC_LEGACY_TM clock used for host
 	 * timeout clock and SW can choose TMCLK or SDCLK for hardware
-- 
2.27.0