[PATCH v2 05/10] PCI: aardvark: Add clock support

[Marek Behún]

From: Miquel Raynal <miquel.raynal at bootlin.com>

The IP relies on a gated clock. When we will add S2RAM support, this
clock will need to be resumed before any PCIe registers are
accessed. Add support for this clock.

Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
Signed-off-by: Pali Rohár <pali at kernel.org>
Signed-off-by: Marek Behún <kabel at kernel.org>
---
 drivers/pci/controller/pci-aardvark.c | 32 +++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 03e318bc171f..3beafc893969 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/interrupt.h>
@@ -297,6 +298,7 @@ struct advk_pcie {
 	struct timer_list link_irq_timer;
 	struct pci_bridge_emul bridge;
 	struct gpio_desc *reset_gpio;
+	struct clk *clk;
 	struct phy *phy;
 };
 
@@ -1809,6 +1811,29 @@ static int advk_pcie_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
 		return of_irq_parse_and_map_pci(dev, slot, pin);
 }
 
+static int advk_pcie_setup_clk(struct advk_pcie *pcie)
+{
+	struct device *dev = &pcie->pdev->dev;
+	int ret;
+
+	pcie->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(pcie->clk) && (PTR_ERR(pcie->clk) == -EPROBE_DEFER))
+		return PTR_ERR(pcie->clk);
+
+	/* Old bindings miss the clock handle */
+	if (IS_ERR(pcie->clk)) {
+		dev_warn(dev, "Clock unavailable (%ld)\n", PTR_ERR(pcie->clk));
+		pcie->clk = NULL;
+		return 0;
+	}
+
+	ret = clk_prepare_enable(pcie->clk);
+	if (ret)
+		dev_err(dev, "Clock initialization failed (%d)\n", ret);
+
+	return ret;
+}
+
 static void advk_pcie_disable_phy(struct advk_pcie *pcie)
 {
 	phy_power_off(pcie->phy);
@@ -2000,6 +2025,10 @@ static int advk_pcie_probe(struct platform_device *pdev)
 			 slot_power_limit / 1000,
 			 (slot_power_limit / 100) % 10);
 
+	ret = advk_pcie_setup_clk(pcie);
+	if (ret)
+		return ret;
+
 	ret = advk_pcie_setup_phy(pcie);
 	if (ret)
 		return ret;
@@ -2122,6 +2151,9 @@ static int advk_pcie_remove(struct platform_device *pdev)
 	/* Disable phy */
 	advk_pcie_disable_phy(pcie);
 
+	/* Disable clock */
+	clk_disable_unprepare(pcie->clk);
+
 	return 0;
 }
 
-- 
2.35.1