Re: [PATCH 29/30] PCI: tegra: Add support for GPIO based PCIe reset

[Thierry Reding <thierry.reding@gmail.com>]

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On Thu, Apr 11, 2019 at 10:33:54PM +0530, Manikanta Maddireddy wrote:
> Add support for GPIO based PERST# instead of SFIO mode controller by AFI.
> GPIO number comes from per port PCIe device tree node.
> 
> Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
> ---
>  drivers/pci/controller/pci-tegra.c | 37 +++++++++++++++++++++++++-----
>  1 file changed, 31 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c
> index 4a91c9fb3a9d..75873e6627f9 100644
> --- a/drivers/pci/controller/pci-tegra.c
> +++ b/drivers/pci/controller/pci-tegra.c
> @@ -17,6 +17,7 @@
>  #include <linux/debugfs.h>
>  #include <linux/delay.h>
>  #include <linux/export.h>
> +#include <linux/gpio.h>
>  #include <linux/interrupt.h>
>  #include <linux/iopoll.h>
>  #include <linux/irq.h>
> @@ -26,6 +27,7 @@
>  #include <linux/module.h>
>  #include <linux/msi.h>
>  #include <linux/of_address.h>
> +#include <linux/of_gpio.h>
>  #include <linux/of_pci.h>
>  #include <linux/of_platform.h>
>  #include <linux/pci.h>
> @@ -406,6 +408,7 @@ struct tegra_pcie_port {
>  
>  	int n_gpios;
>  	int *gpios;
> +	int rst_gpio;

This should be using GPIO descriptor APIs.

Thierry

>  };
>  
>  struct tegra_pcie_bus {
> @@ -589,15 +592,23 @@ static void tegra_pcie_port_reset(struct tegra_pcie_port *port)
>  	unsigned long value;
>  
>  	/* pulse reset signal */
> -	value = afi_readl(port->pcie, ctrl);
> -	value &= ~AFI_PEX_CTRL_RST;
> -	afi_writel(port->pcie, value, ctrl);
> +	if (gpio_is_valid(port->rst_gpio)) {
> +		gpio_set_value(port->rst_gpio, 0);
> +	} else {
> +		value = afi_readl(port->pcie, ctrl);
> +		value &= ~AFI_PEX_CTRL_RST;
> +		afi_writel(port->pcie, value, ctrl);
> +	}
>  
>  	usleep_range(1000, 2000);
>  
> -	value = afi_readl(port->pcie, ctrl);
> -	value |= AFI_PEX_CTRL_RST;
> -	afi_writel(port->pcie, value, ctrl);
> +	if (gpio_is_valid(port->rst_gpio)) {
> +		gpio_set_value(port->rst_gpio, 1);
> +	} else {
> +		value = afi_readl(port->pcie, ctrl);
> +		value |= AFI_PEX_CTRL_RST;
> +		afi_writel(port->pcie, value, ctrl);
> +	}
>  }
>  
>  static void tegra_pcie_enable_rp_features(struct tegra_pcie_port *port)
> @@ -2241,6 +2252,20 @@ static int tegra_pcie_parse_plat_dt(struct tegra_pcie_port *port,
>  		}
>  	}
>  
> +	port->rst_gpio = of_get_named_gpio(np, "nvidia,rst-gpio", 0);
> +	if (gpio_is_valid(port->rst_gpio)) {
> +		err = devm_gpio_request(dev, port->rst_gpio, "pex_rst_gpio");
> +		if (err < 0) {
> +			dev_err(dev, "rst_gpio request failed: %d\n", err);
> +			return err;
> +		}
> +		err = gpio_direction_output(port->rst_gpio, 0);
> +		if (err < 0) {
> +			dev_err(dev, "rst_gpio set o/p failed: %d\n", err);
> +			return err;
> +		}
> +	}
> +
>  	return 0;
>  }
>  
> -- 
> 2.17.1
> 

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