pci: mx6: Implement reset callback
Add a callback so that a board can implement it's own specific routine to
toggle the port's #PERST line or #define a GPIO to do so.
Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/drivers/pci/pcie_imx.c b/drivers/pci/pcie_imx.c
index 0a74867..34377e9 100644
--- a/drivers/pci/pcie_imx.c
+++ b/drivers/pci/pcie_imx.c
@@ -15,6 +15,7 @@
#include <asm/arch/clock.h>
#include <asm/arch/iomux.h>
#include <asm/arch/crm_regs.h>
+#include <asm/gpio.h>
#include <asm/io.h>
#include <asm/sizes.h>
#include <errno.h>
@@ -450,6 +451,47 @@
return 0;
}
+__weak int imx6_pcie_toggle_reset(void)
+{
+ /*
+ * See 'PCI EXPRESS BASE SPECIFICATION, REV 3.0, SECTION 6.6.1'
+ * for detailed understanding of the PCIe CR reset logic.
+ *
+ * The PCIe #PERST reset line _MUST_ be connected, otherwise your
+ * design does not conform to the specification. You must wait at
+ * least 20 mS after de-asserting the #PERST so the EP device can
+ * do self-initialisation.
+ *
+ * In case your #PERST pin is connected to a plain GPIO pin of the
+ * CPU, you can define CONFIG_PCIE_IMX_PERST_GPIO in your board's
+ * configuration file and the condition below will handle the rest
+ * of the reset toggling.
+ *
+ * In case your #PERST toggling logic is more complex, for example
+ * connected via CPLD or somesuch, you can override this function
+ * in your board file and implement reset logic as needed. You must
+ * not forget to wait at least 20 mS after de-asserting #PERST in
+ * this case either though.
+ *
+ * In case your #PERST line of the PCIe EP device is not connected
+ * at all, your design is broken and you should fix your design,
+ * otherwise you will observe problems like for example the link
+ * not coming up after rebooting the system back from running Linux
+ * that uses the PCIe as well OR the PCIe link might not come up in
+ * Linux at all in the first place since it's in some non-reset
+ * state due to being previously used in U-Boot.
+ */
+#ifdef CONFIG_PCIE_IMX_PERST_GPIO
+ gpio_direction_output(CONFIG_PCIE_IMX_PERST_GPIO, 0);
+ mdelay(20);
+ gpio_set_value(CONFIG_PCIE_IMX_PERST_GPIO, 1);
+ mdelay(20);
+#else
+ puts("WARNING: Make sure the PCIe #PERST line is connected!\n");
+#endif
+ return 0;
+}
+
static int imx6_pcie_deassert_core_reset(void)
{
struct iomuxc *iomuxc_regs = (struct iomuxc *)IOMUXC_BASE_ADDR;
@@ -466,10 +508,9 @@
* Wait for the clock to settle a bit, when the clock are sourced
* from the CPU, we need about 30mS to settle.
*/
- mdelay(30);
+ mdelay(50);
- /* FIXME: GPIO reset goes here */
- mdelay(100);
+ imx6_pcie_toggle_reset();
return 0;
}