PCI: xilinx-nwl: Enable the clock through CCF

commit de0a01f5296651d3a539f2d23d0db8f359483696 upstream.

Enable PCIe reference clock. There is no remove function that's why
this should be enough for simple operation.
Normally this clock is enabled by default by firmware but there are
usecases where this clock should be enabled by driver itself.
It is also good that PCIe clock is recorded in a clock framework.

Link: https://lore.kernel.org/r/ee6997a08fab582b1c6de05f8be184f3fe8d5357.1624618100.git.michal.simek@xilinx.com
Fixes: ab597d35ef11 ("PCI: xilinx-nwl: Add support for Xilinx NWL PCIe Host Controller")
Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>
Signed-off-by: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pci/host/pcie-xilinx-nwl.c b/drivers/pci/host/pcie-xilinx-nwl.c
index 981a5195686f3c084476218a6c13061aa1119fff..6812a1b49fa8a6009ce16be525b511d06fd3d7e8 100644 (file)
--- a/drivers/pci/host/pcie-xilinx-nwl.c
+++ b/drivers/pci/host/pcie-xilinx-nwl.c
@@ -10,6 +10,7 @@
  * (at your option) any later version.
  */
 
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
@@ -171,6 +172,7 @@ struct nwl_pcie {
        u8 root_busno;
        struct nwl_msi msi;
        struct irq_domain *legacy_irq_domain;
+       struct clk *clk;
        raw_spinlock_t leg_mask_lock;
 };
 
@@ -852,6 +854,16 @@ static int nwl_pcie_probe(struct platform_device *pdev)
                return err;
        }
 
+       pcie->clk = devm_clk_get(dev, NULL);
+       if (IS_ERR(pcie->clk))
+               return PTR_ERR(pcie->clk);
+
+       err = clk_prepare_enable(pcie->clk);
+       if (err) {
+               dev_err(dev, "can't enable PCIe ref clock\n");
+               return err;
+       }
+
        err = nwl_pcie_bridge_init(pcie);
        if (err) {
                dev_err(dev, "HW Initialization failed\n");