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.ray...@bootlin.com>
---
 drivers/pci/controller/pci-aardvark.c | 29 +++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/pci/controller/pci-aardvark.c 
b/drivers/pci/controller/pci-aardvark.c
index 0f50163ae072..b1b8897d2d28 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -8,6 +8,7 @@
  * Author: Hezi Shahmoon <hezi.shahm...@marvell.com>
  */
 
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
@@ -187,6 +188,7 @@
 
 struct advk_pcie {
        struct platform_device *pdev;
+       struct clk *clk;
        void __iomem *base;
        struct list_head resources;
        struct irq_domain *irq_domain;
@@ -973,6 +975,29 @@ static int advk_pcie_parse_request_of_pci_ranges(struct 
advk_pcie *pcie)
        return err;
 }
 
+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 int advk_pcie_probe(struct platform_device *pdev)
 {
        struct device *dev = &pdev->dev;
@@ -1008,6 +1033,10 @@ static int advk_pcie_probe(struct platform_device *pdev)
                return ret;
        }
 
+       ret = advk_pcie_setup_clk(pcie);
+       if (ret)
+               return ret;
+
        advk_pcie_setup_hw(pcie);
 
        advk_sw_pci_bridge_init(pcie);
-- 
2.19.1

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