// SPDX-License-Identifier: GPL-2.0
/* uio_fsl_elbc_gpcm: UIO driver for eLBC/GPCM peripherals

   Copyright (C) 2014 Linutronix GmbH
     Author: John Ogness <john.ogness@linutronix.de>

   This driver provides UIO access to memory of a peripheral connected
   to the Freescale enhanced local bus controller (eLBC) interface
   using the general purpose chip-select mode (GPCM).

   Here is an example of the device tree entries:

        localbus@ffe05000 {
                ranges = <0x2 0x0 0x0 0xff810000 0x10000>;

                dpm@2,0 {
                        compatible = "fsl,elbc-gpcm-uio";
                        reg = <0x2 0x0 0x10000>;
                        elbc-gpcm-br = <0xff810800>;
                        elbc-gpcm-or = <0xffff09f7>;
                        interrupt-parent = <&mpic>;
                        interrupts = <4 1>;
                        device_type = "netx5152";
                        uio_name = "netx_custom";
                        netx5152,init-win0-offset = <0x0>;
                };
        };

   Only the entries reg (to identify bank) and elbc-gpcm-* (initial BR/OR
   values) are required. The entries interrupt*, device_type, and uio_name
   are optional (as well as any type-specific options such as
   netx5152,init-win0-offset). As long as no interrupt handler is needed,
   this driver can be used without any type-specific implementation.

   The netx5152 type has been tested to work with the netX 51/52 hardware
   from Hilscher using the Hilscher userspace netX stack.

   The netx5152 type should serve as a model to add new type-specific
   devices as needed.
*/

#include <linux/module.h>
#include <linux/device.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/uio_driver.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>

#include <asm/fsl_lbc.h>

#define MAX_BANKS 8

struct fsl_elbc_gpcm {
        struct device *dev;
        struct fsl_lbc_regs __iomem *lbc;
        u32 bank;
        const char *name;

        void (*init)(struct uio_info *info);
        void (*shutdown)(struct uio_info *info, bool init_err);
        irqreturn_t (*irq_handler)(int irq, struct uio_info *info);
};

static ssize_t reg_show(struct device *dev, struct device_attribute *attr,
                        char *buf);
static ssize_t reg_store(struct device *dev, struct device_attribute *attr,
                         const char *buf, size_t count);

static DEVICE_ATTR(reg_br, 0664, reg_show, reg_store);
static DEVICE_ATTR(reg_or, 0664, reg_show, reg_store);

static struct attribute *uio_fsl_elbc_gpcm_attrs[] = {
        &dev_attr_reg_br.attr,
        &dev_attr_reg_or.attr,
        NULL,
};
ATTRIBUTE_GROUPS(uio_fsl_elbc_gpcm);

static ssize_t reg_show(struct device *dev, struct device_attribute *attr,
                        char *buf)
{
        struct uio_info *info = dev_get_drvdata(dev);
        struct fsl_elbc_gpcm *priv = info->priv;
        struct fsl_lbc_bank *bank = &priv->lbc->bank[priv->bank];

        if (attr == &dev_attr_reg_br) {
                return scnprintf(buf, PAGE_SIZE, "0x%08x\n",
                                 in_be32(&bank->br));

        } else if (attr == &dev_attr_reg_or) {
                return scnprintf(buf, PAGE_SIZE, "0x%08x\n",
                                 in_be32(&bank->or));
        }

        return 0;
}

static ssize_t reg_store(struct device *dev, struct device_attribute *attr,
                         const char *buf, size_t count)
{
        struct uio_info *info = dev_get_drvdata(dev);
        struct fsl_elbc_gpcm *priv = info->priv;
        struct fsl_lbc_bank *bank = &priv->lbc->bank[priv->bank];
        unsigned long val;
        u32 reg_br_cur;
        u32 reg_or_cur;
        u32 reg_new;

        /* parse use input */
        if (kstrtoul(buf, 0, &val) != 0)
                return -EINVAL;
        reg_new = (u32)val;

        /* read current values */
        reg_br_cur = in_be32(&bank->br);
        reg_or_cur = in_be32(&bank->or);

        if (attr == &dev_attr_reg_br) {
                /* not allowed to change effective base address */
                if ((reg_br_cur & reg_or_cur & BR_BA) !=
                    (reg_new & reg_or_cur & BR_BA)) {
                        return -EINVAL;
                }

                /* not allowed to change mode */
                if ((reg_new & BR_MSEL) != BR_MS_GPCM)
                        return -EINVAL;

                /* write new value (force valid) */
                out_be32(&bank->br, reg_new | BR_V);

        } else if (attr == &dev_attr_reg_or) {
                /* not allowed to change access mask */
                if ((reg_or_cur & OR_GPCM_AM) != (reg_new & OR_GPCM_AM))
                        return -EINVAL;

                /* write new value */
                out_be32(&bank->or, reg_new);

        } else {
                return -EINVAL;
        }

        return count;
}

#ifdef CONFIG_UIO_FSL_ELBC_GPCM_NETX5152
#define DPM_HOST_WIN0_OFFSET    0xff00
#define DPM_HOST_INT_STAT0      0xe0
#define DPM_HOST_INT_EN0        0xf0
#define DPM_HOST_INT_MASK       0xe600ffff
#define DPM_HOST_INT_GLOBAL_EN  0x80000000

static irqreturn_t netx5152_irq_handler(int irq, struct uio_info *info)
{
        void __iomem *reg_int_en = info->mem[0].internal_addr +
                                        DPM_HOST_WIN0_OFFSET +
                                        DPM_HOST_INT_EN0;
        void __iomem *reg_int_stat = info->mem[0].internal_addr +
                                        DPM_HOST_WIN0_OFFSET +
                                        DPM_HOST_INT_STAT0;

        /* check if an interrupt is enabled and active */
        if ((ioread32(reg_int_en) & ioread32(reg_int_stat) &
             DPM_HOST_INT_MASK) == 0) {
                return IRQ_NONE;
        }

        /* disable interrupts */
        iowrite32(ioread32(reg_int_en) & ~DPM_HOST_INT_GLOBAL_EN, reg_int_en);

        return IRQ_HANDLED;
}

static void netx5152_init(struct uio_info *info)
{
        unsigned long win0_offset = DPM_HOST_WIN0_OFFSET;
        struct fsl_elbc_gpcm *priv = info->priv;
        const void *prop;

        /* get an optional initial win0 offset */
        prop = of_get_property(priv->dev->of_node,
                               "netx5152,init-win0-offset", NULL);
        if (prop)
                win0_offset = of_read_ulong(prop, 1);

        /* disable interrupts */
        iowrite32(0, info->mem[0].internal_addr + win0_offset +
                     DPM_HOST_INT_EN0);
}

static void netx5152_shutdown(struct uio_info *info, bool init_err)
{
        if (init_err)
                return;

        /* disable interrupts */
        iowrite32(0, info->mem[0].internal_addr + DPM_HOST_WIN0_OFFSET +
                     DPM_HOST_INT_EN0);
}
#endif

static void setup_periph(struct fsl_elbc_gpcm *priv,
                                   const char *type)
{
#ifdef CONFIG_UIO_FSL_ELBC_GPCM_NETX5152
        if (strcmp(type, "netx5152") == 0) {
                priv->irq_handler = netx5152_irq_handler;
                priv->init = netx5152_init;
                priv->shutdown = netx5152_shutdown;
                priv->name = "netX 51/52";
                return;
        }
#endif
}

static int check_of_data(struct fsl_elbc_gpcm *priv,
                                   struct resource *res,
                                   u32 reg_br, u32 reg_or)
{
        /* check specified bank */
        if (priv->bank >= MAX_BANKS) {
                dev_err(priv->dev, "invalid bank\n");
                return -ENODEV;
        }

        /* check specified mode (BR_MS_GPCM is 0) */
        if ((reg_br & BR_MSEL) != BR_MS_GPCM) {
                dev_err(priv->dev, "unsupported mode\n");
                return -ENODEV;
        }

        /* check specified mask vs. resource size */
        if ((~(reg_or & OR_GPCM_AM) + 1) != resource_size(res)) {
                dev_err(priv->dev, "address mask / size mismatch\n");
                return -ENODEV;
        }

        /* check specified address */
        if ((reg_br & reg_or & BR_BA) != fsl_lbc_addr(res->start)) {
                dev_err(priv->dev, "base address mismatch\n");
                return -ENODEV;
        }

        return 0;
}

static int get_of_data(struct fsl_elbc_gpcm *priv, struct device_node *node,
                       struct resource *res, u32 *reg_br,
                       u32 *reg_or, unsigned int *irq, char **name)
{
        const char *dt_name;
        const char *type;
        int ret;

        /* get the memory resource */
        ret = of_address_to_resource(node, 0, res);
        if (ret) {
                dev_err(priv->dev, "failed to get resource\n");
                return ret;
        }

        /* get the bank number */
        ret = of_property_read_u32(node, "reg", &priv->bank);
        if (ret) {
                dev_err(priv->dev, "failed to get bank number\n");
                return ret;
        }

        /* get BR value to set */
        ret = of_property_read_u32(node, "elbc-gpcm-br", reg_br);
        if (ret) {
                dev_err(priv->dev, "missing elbc-gpcm-br value\n");
                return ret;
        }

        /* get OR value to set */
        ret = of_property_read_u32(node, "elbc-gpcm-or", reg_or);
        if (ret) {
                dev_err(priv->dev, "missing elbc-gpcm-or value\n");
                return ret;
        }

        /* get optional peripheral type */
        priv->name = "generic";
        if (of_property_read_string(node, "device_type", &type) == 0)
                setup_periph(priv, type);

        /* get optional irq value */
        *irq = irq_of_parse_and_map(node, 0);

        /* sanity check device tree data */
        ret = check_of_data(priv, res, *reg_br, *reg_or);
        if (ret)
                return ret;

        /* get optional uio name */
        if (of_property_read_string(node, "uio_name", &dt_name) != 0)
                dt_name = "eLBC_GPCM";
        *name = devm_kstrdup(priv->dev, dt_name, GFP_KERNEL);
        if (!*name)
                return -ENOMEM;

        return 0;
}

static int uio_fsl_elbc_gpcm_probe(struct platform_device *pdev)
{
        struct device_node *node = pdev->dev.of_node;
        struct fsl_elbc_gpcm *priv;
        struct uio_info *info;
        char *uio_name = NULL;
        struct resource res;
        unsigned int irq;
        u32 reg_br_cur;
        u32 reg_or_cur;
        u32 reg_br_new;
        u32 reg_or_new;
        int ret;

        if (!fsl_lbc_ctrl_dev || !fsl_lbc_ctrl_dev->regs)
                return -ENODEV;

        /* allocate private data */
        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;
        priv->dev = &pdev->dev;
        priv->lbc = fsl_lbc_ctrl_dev->regs;

        /* get device tree data */
        ret = get_of_data(priv, node, &res, &reg_br_new, &reg_or_new,
                          &irq, &uio_name);
        if (ret)
                return ret;

        /* allocate UIO structure */
        info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
        if (!info)
                return -ENOMEM;

        /* get current BR/OR values */
        reg_br_cur = in_be32(&priv->lbc->bank[priv->bank].br);
        reg_or_cur = in_be32(&priv->lbc->bank[priv->bank].or);

        /* if bank already configured, make sure it matches */
        if ((reg_br_cur & BR_V)) {
                if ((reg_br_cur & BR_MSEL) != BR_MS_GPCM ||
                    (reg_br_cur & reg_or_cur & BR_BA)
                     != fsl_lbc_addr(res.start)) {
                        dev_err(priv->dev,
                                "bank in use by another peripheral\n");
                        return -ENODEV;
                }

                /* warn if behavior settings changing */
                if ((reg_br_cur & ~(BR_BA | BR_V)) !=
                    (reg_br_new & ~(BR_BA | BR_V))) {
                        dev_warn(priv->dev,
                                 "modifying BR settings: 0x%08x -> 0x%08x",
                                 reg_br_cur, reg_br_new);
                }
                if ((reg_or_cur & ~OR_GPCM_AM) != (reg_or_new & ~OR_GPCM_AM)) {
                        dev_warn(priv->dev,
                                 "modifying OR settings: 0x%08x -> 0x%08x",
                                 reg_or_cur, reg_or_new);
                }
        }

        /* configure the bank (force base address and GPCM) */
        reg_br_new &= ~(BR_BA | BR_MSEL);
        reg_br_new |= fsl_lbc_addr(res.start) | BR_MS_GPCM | BR_V;
        out_be32(&priv->lbc->bank[priv->bank].or, reg_or_new);
        out_be32(&priv->lbc->bank[priv->bank].br, reg_br_new);

        /* map the memory resource */
        info->mem[0].internal_addr = ioremap(res.start, resource_size(&res));
        if (!info->mem[0].internal_addr) {
                dev_err(priv->dev, "failed to map chip region\n");
                return -ENODEV;
        }

        /* set all UIO data */
        info->mem[0].name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn", node);
        if (!info->mem[0].name) {
                ret = -ENODEV;
                goto out_err3;
        }

        info->mem[0].addr = res.start;
        info->mem[0].size = resource_size(&res);
        info->mem[0].memtype = UIO_MEM_PHYS;
        info->priv = priv;
        info->name = uio_name;
        info->version = "0.0.1";
        if (irq) {
                if (priv->irq_handler) {
                        info->irq = irq;
                        info->irq_flags = IRQF_SHARED;
                        info->handler = priv->irq_handler;
                } else {
                        irq = 0;
                        dev_warn(priv->dev, "ignoring irq, no handler\n");
                }
        }

        if (priv->init)
                priv->init(info);

        /* register UIO device */
        if (uio_register_device(priv->dev, info) != 0) {
                dev_err(priv->dev, "UIO registration failed\n");
                ret = -ENODEV;
                goto out_err2;
        }

        /* store private data */
        platform_set_drvdata(pdev, info);

        dev_info(priv->dev,
                 "eLBC/GPCM device (%s) at 0x%llx, bank %d, irq=%d\n",
                 priv->name, (unsigned long long)res.start, priv->bank,
                 irq ? : -1);

        return 0;
out_err2:
        if (priv->shutdown)
                priv->shutdown(info, true);

out_err3:
        iounmap(info->mem[0].internal_addr);
        return ret;
}

static void uio_fsl_elbc_gpcm_remove(struct platform_device *pdev)
{
        struct uio_info *info = platform_get_drvdata(pdev);
        struct fsl_elbc_gpcm *priv = info->priv;

        platform_set_drvdata(pdev, NULL);
        uio_unregister_device(info);
        if (priv->shutdown)
                priv->shutdown(info, false);
        iounmap(info->mem[0].internal_addr);

}

static const struct of_device_id uio_fsl_elbc_gpcm_match[] = {
        { .compatible = "fsl,elbc-gpcm-uio", },
        {}
};
MODULE_DEVICE_TABLE(of, uio_fsl_elbc_gpcm_match);

static struct platform_driver uio_fsl_elbc_gpcm_driver = {
        .driver = {
                .name = "fsl,elbc-gpcm-uio",
                .of_match_table = uio_fsl_elbc_gpcm_match,
                .dev_groups = uio_fsl_elbc_gpcm_groups,
        },
        .probe = uio_fsl_elbc_gpcm_probe,
        .remove = uio_fsl_elbc_gpcm_remove,
};
module_platform_driver(uio_fsl_elbc_gpcm_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Ogness <john.ogness@linutronix.de>");
MODULE_DESCRIPTION("Freescale Enhanced Local Bus Controller GPCM driver");