Re: [Xen-devel] [RFC v3 2/4] xen/linux_compat: Add a Linux compat header

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Sameer,

On 05/12/17 03:59, Sameer Goel wrote:
> For porting files from Linux it is useful to have a Linux API to Xen API
> mapping header at a common location.
> This file adds common API functions and other defines that are needed for
> porting arm SMMU drivers.
>
> ---
>   xen/include/xen/linux_compat.h | 106 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 106 insertions(+)
>   create mode 100644 xen/include/xen/linux_compat.h
>
> diff --git a/xen/include/xen/linux_compat.h b/xen/include/xen/linux_compat.h
> new file mode 100644
> index 0000000..217e0cc
> --- /dev/null
> +++ b/xen/include/xen/linux_compat.h
> @@ -0,0 +1,106 @@
> +/******************************************************************************
> + * include/xen/linux_compat.h
> + *
> + * Compatibility defines for porting code from Linux to Xen
> + *
> + * Copyright (c) 2017 Linaro Limited
> + *
> + * 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, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef __XEN_LINUX_COMPAT_H__
> +#define __XEN_LINUX_COMPAT_H__
> +
> +#include <asm/types.h>
> +
> +typedef paddr_t phys_addr_t;
> +typedef paddr_t dma_addr_t;
> +
> +/* Alias to Xen device tree helpers */
> +#define device_node dt_device_node
> +#define of_phandle_args dt_phandle_args
> +#define of_device_id dt_device_match
> +#define of_match_node dt_match_node
> +#define of_property_read_u32(np, pname, out) (!dt_property_read_u32(np, pname, 
> out))
> +#define of_property_read_bool dt_property_read_bool
> +#define of_parse_phandle_with_args dt_parse_phandle_with_args
> +/* The user should consider if it is safe to treat mutex as a spinlock */
I am against defining mutex as spinlock in a generic header. People will 
overlook it and it is hardly going to be detected in a verbatim port.
This should be done on the case by case basis.

> +#define mutex spinlock_t
> +#define mutex_init spin_lock_init
> +#define mutex_lock spin_lock
> +#define mutex_unlock spin_unlock
> +
> +#define ilog2 LOG_2
There is only one user of LOG_2 in Xen. So wouldn't it be better to 
rename directly to ilog2?
> +
> +#define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us) \
> +({ \
> +    s_time_t deadline = NOW() + MICROSECS(timeout_us); \
> +    for (;;) \
> +    { \
> +        (val) = op(addr); \
> +        if ( cond ) \
> +            break; \
> +        if ( NOW() > deadline ) \
> +        { \
> +            (val) = op(addr); \
> +            break; \
> +        } \
> +        udelay(sleep_us); \
> +    } \
> +    (cond) ? 0 : -ETIMEDOUT; \
> +})
> +
> +#define readl_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
> +    readx_poll_timeout(readl_relaxed, addr, val, cond, delay_us, timeout_us)
I don't think putting read* macros in a common header is necessary. 
Their use in Linux is very limited.
> +
> +/* Xen: Helpers for IRQ functions */
> +#define request_irq(irq, func, flags, name, dev) request_irq(irq, flags, func, 
> name, dev)
> +#define free_irq release_irq
> +
> +enum irqreturn {
> +    IRQ_NONE    = (0 << 0),
> +    IRQ_HANDLED = (1 << 0),
> +    IRQ_WAKE_THREAD = (2 << 0),
> +};
> +
> +typedef enum irqreturn irqreturn_t;
> +
> +/* Device logger functions */
> +#define dev_print(dev, lvl, fmt, ...)                       \
> +     printk(lvl fmt, ## __VA_ARGS__)
> +
> +#define dev_dbg(dev, fmt, ...) dev_print(dev, XENLOG_DEBUG, fmt, ## 
> __VA_ARGS__)
> +#define dev_notice(dev, fmt, ...) dev_print(dev, XENLOG_INFO, fmt, ## 
> __VA_ARGS__)
> +#define dev_warn(dev, fmt, ...) dev_print(dev, XENLOG_WARNING, fmt, ## 
> __VA_ARGS__)
> +#define dev_err(dev, fmt, ...) dev_print(dev, XENLOG_ERR, fmt, ## __VA_ARGS__)
> +#define dev_info(dev, fmt, ...) dev_print(dev, XENLOG_INFO, fmt, ## 
> __VA_ARGS__)
> +
> +#define dev_err_ratelimited(dev, fmt, ...)                  \
> +     dev_print(dev, XENLOG_ERR, fmt, ## __VA_ARGS__)
> +
> +#define dev_name(dev) dt_node_full_name(dev_to_dt(dev))
> +
> +/* Alias to Xen allocation helpers */
> +#define kfree xfree
> +#define kmalloc(size, flags)        _xmalloc(size, sizeof(void *))
> +#define kzalloc(size, flags)        _xzalloc(size, sizeof(void *))
> +#define devm_kzalloc(dev, size, flags)  _xzalloc(size, sizeof(void *))
> +#define kmalloc_array(size, n, flags)   _xmalloc_array(size, sizeof(void *), n)
> +
> +/* Alias to Xen time functions */
> +#define ktime_t s_time_t
> +#define ktime_add_us(t,i)       (NOW() + MICROSECS(i))
> +#define ktime_compare(t,i)      (NOW() > (i))
> +
> +#endif /* __XEN_LINUX_COMPAT_H__ */
Cheers,

--
Julien Grall

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