dwgpio.c

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/*
 * Copyright (C) 2025 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <ipxe/devtree.h>
#include <ipxe/fdt.h>
#include <ipxe/gpio.h>
#include "dwgpio.h"

/** @file
 *
 * Synopsys DesignWare GPIO driver
 *
 */

/******************************************************************************
 *
 * GPIO port group
 *
 ******************************************************************************
 */

/**
 * Probe port group
 *
 * @v dt                Devicetree device
 * @v offset            Starting node offset
 * @ret rc              Return status code
 */
static int dwgpio_group_probe ( struct dt_device *dt, unsigned int offset ) {
        struct dwgpio_group *group;
        int rc;

        /* Allocate and initialise structure */
        group = zalloc ( sizeof ( *group ) );
        if ( ! group ) {
                rc = -ENOMEM;
                goto err_alloc;
        }
        dt_set_drvdata ( dt, group );

        /* Map registers */
        group->regs = dt_ioremap ( dt, offset, 0, 0 );
        if ( ! group->regs ) {
                rc = -ENODEV;
                goto err_ioremap;
        }

        /* Probe child ports */
        if ( ( rc = dt_probe_children ( dt, offset ) ) != 0 )
                goto err_children;

        return 0;

        dt_remove_children ( dt );
 err_children:
        iounmap ( group->regs );
 err_ioremap:
        free ( group );
 err_alloc:
        return rc;
}

/**
 * Remove port group
 *
 * @v dt                Devicetree device
 */
static void dwgpio_group_remove ( struct dt_device *dt ) {
        struct dwgpio_group *group = dt_get_drvdata ( dt );

        /* Remove child ports */
        dt_remove_children ( dt );

        /* Unmap registers */
        iounmap ( group->regs );

        /* Free device */
        free ( group );
}

/** DesignWare GPIO port group compatible model identifiers */
static const char * dwgpio_group_ids[] = {
        "snps,dw-apb-gpio",
};

/** DesignWare GPIO port group devicetree driver */
struct dt_driver dwgpio_group_driver __dt_driver = {
        .name = "dwgpio-group",
        .ids = dwgpio_group_ids,
        .id_count = ( sizeof ( dwgpio_group_ids ) /
                      sizeof ( dwgpio_group_ids[0] ) ),
        .probe = dwgpio_group_probe,
        .remove = dwgpio_group_remove,
};

/******************************************************************************
 *
 * GPIO port
 *
 ******************************************************************************
 */

/**
 * Dump GPIO port status
 *
 * @v dwgpio            DesignWare GPIO port
 */
static inline void dwgpio_dump ( struct dwgpio *dwgpio ) {

        DBGC2 ( dwgpio, "DWGPIO %s dr %#08x ddr %#08x ctl %#08x\n",
                dwgpio->name, readl ( dwgpio->swport + DWGPIO_SWPORT_DR ),
                readl ( dwgpio->swport + DWGPIO_SWPORT_DDR ),
                readl ( dwgpio->swport + DWGPIO_SWPORT_CTL ) );
}

/**
 * Get current GPIO input value
 *
 * @v gpios             GPIO controller
 * @v gpio              GPIO pin
 * @ret active          Pin is in the active state
 */
static int dwgpio_in ( struct gpios *gpios, struct gpio *gpio ) {
        struct dwgpio *dwgpio = gpios->priv;
        uint32_t ext;

        /* Read external port status */
        ext = readl ( dwgpio->ext );
        return ( ( ( ext >> gpio->index ) ^ gpio->config ) & 1 );
}

/**
 * Set current GPIO output value
 *
 * @v gpios             GPIO controller
 * @v gpio              GPIO pin
 * @v active            Set pin to active state
 */
static void dwgpio_out ( struct gpios *gpios, struct gpio *gpio, int active ) {
        struct dwgpio *dwgpio = gpios->priv;
        uint32_t mask = ( 1UL << gpio->index );
        uint32_t dr;

        /* Update data register */
        dr = readl ( dwgpio->swport + DWGPIO_SWPORT_DR );
        dr &= ~mask;
        if ( ( ( !! active ) ^ gpio->config ) & 1 )
                dr |= mask;
        writel ( dr, ( dwgpio->swport + DWGPIO_SWPORT_DR ) );
        dwgpio_dump ( dwgpio );
}

/**
 * Configure GPIO pin
 *
 * @v gpios             GPIO controller
 * @v gpio              GPIO pin
 * @v config            Configuration
 * @ret rc              Return status code
 */
static int dwgpio_config ( struct gpios *gpios, struct gpio *gpio,
                           unsigned int config ) {
        struct dwgpio *dwgpio = gpios->priv;
        uint32_t mask = ( 1UL << gpio->index );
        uint32_t ddr;
        uint32_t ctl;

        /* Update data direction and control registers */
        ddr = readl ( dwgpio->swport + DWGPIO_SWPORT_DDR );
        ctl = readl ( dwgpio->swport + DWGPIO_SWPORT_CTL );
        ctl &= ~mask;
        ddr &= ~mask;
        if ( config & GPIO_CFG_OUTPUT )
                ddr |= mask;
        writel ( ctl, ( dwgpio->swport + DWGPIO_SWPORT_CTL ) );
        writel ( ddr, ( dwgpio->swport + DWGPIO_SWPORT_DDR ) );
        dwgpio_dump ( dwgpio );

        return 0;
}

/** GPIO operations */
static struct gpio_operations dwgpio_operations = {
        .in = dwgpio_in,
        .out = dwgpio_out,
        .config = dwgpio_config,
};

/**
 * Probe port
 *
 * @v dt                Devicetree device
 * @v offset            Starting node offset
 * @ret rc              Return status code
 */
static int dwgpio_probe ( struct dt_device *dt, unsigned int offset ) {
        struct dt_device *parent;
        struct dwgpio_group *group;
        struct dwgpio *dwgpio;
        struct gpios *gpios;
        uint32_t count;
        uint64_t port;
        int rc;

        /* Get number of GPIOs */
        if ( ( rc = fdt_u32 ( &sysfdt, offset, "nr-gpios-snps",
                              &count ) ) != 0 ) {
                goto err_count;
        }
        assert ( count <= DWGPIO_MAX_COUNT );

        /* Allocate and initialise device */
        gpios = alloc_gpios ( count, sizeof ( *dwgpio ) );
        if ( ! gpios ) {
                rc = -ENOMEM;
                goto err_alloc;
        }
        dt_set_drvdata ( dt, gpios );
        gpios->dev = &dt->dev;
        gpios_init ( gpios, &dwgpio_operations );
        dwgpio = gpios->priv;
        dwgpio->name = dt->name;

        /* Identify group */
        parent = dt_parent ( dt );
        if ( parent->driver != &dwgpio_group_driver ) {
                DBGC ( dwgpio, "DWGPIO %s has invalid parent %s\n",
                       dwgpio->name, parent->name );
                rc = -EINVAL;
                goto err_parent;
        }
        group = dt_get_drvdata ( parent );

        /* Identify port */
        if ( ( rc = fdt_reg ( &sysfdt, offset, &port ) ) != 0 ) {
                DBGC ( dwgpio, "DWGPIO %s could not get port number: %s\n",
                       dwgpio->name, strerror ( rc ) );
                goto err_port;
        }
        dwgpio->port = port;
        DBGC ( dwgpio, "DWGPIO %s is %s port %d (%d GPIOs)\n",
               dwgpio->name, parent->name, dwgpio->port, gpios->count );

        /* Map registers */
        dwgpio->swport = ( group->regs + DWGPIO_SWPORT ( port ) );
        dwgpio->ext = ( group->regs + DWGPIO_EXT_PORT ( port ) );
        dwgpio_dump ( dwgpio );

        /* Record original register values */
        dwgpio->dr = readl ( dwgpio->swport + DWGPIO_SWPORT_DR );
        dwgpio->ddr = readl ( dwgpio->swport + DWGPIO_SWPORT_DDR );
        dwgpio->ctl = readl ( dwgpio->swport + DWGPIO_SWPORT_CTL );

        /* Register GPIO controller */
        if ( ( rc = gpios_register ( gpios ) ) != 0 ) {
                DBGC ( dwgpio, "DWGPIO %s could not register: %s\n",
                       dwgpio->name, strerror ( rc ) );
                goto err_register;
        }

        return 0;

        gpios_unregister ( gpios );
 err_register:
 err_port:
 err_parent:
        gpios_nullify ( gpios );
        gpios_put ( gpios );
 err_alloc:
 err_count:
        return rc;
}

/**
 * Remove port
 *
 * @v dt                Devicetree device
 */
static void dwgpio_remove ( struct dt_device *dt ) {
        struct gpios *gpios = dt_get_drvdata ( dt );
        struct dwgpio *dwgpio = gpios->priv;

        /* Unregister GPIO controller */
        gpios_unregister ( gpios );

        /* Restore original register values */
        writel ( dwgpio->ctl, ( dwgpio->swport + DWGPIO_SWPORT_CTL ) );
        writel ( dwgpio->ddr, ( dwgpio->swport + DWGPIO_SWPORT_DDR ) );
        writel ( dwgpio->dr, ( dwgpio->swport + DWGPIO_SWPORT_DR ) );

        /* Free GPIO device */
        gpios_nullify ( gpios );
        gpios_put ( gpios );
}

/** DesignWare GPIO port compatible model identifiers */
static const char * dwgpio_ids[] = {
        "snps,dw-apb-gpio-port",
};

/** DesignWare GPIO port devicetree driver */
struct dt_driver dwgpio_driver __dt_driver = {
        .name = "dwgpio",
        .ids = dwgpio_ids,
        .id_count = ( sizeof ( dwgpio_ids ) / sizeof ( dwgpio_ids[0] ) ),
        .probe = dwgpio_probe,
        .remove = dwgpio_remove,
};