source: mainline/kernel/arch/sparc64/src/drivers/sgcn.c@ 91ea7c4

/*
 * Copyright (c) 2008 Pavel Rimsky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup sparc64
 * @{
 */
/**
 * @file
 * @brief       SGCN driver.
 */

#include <arch.h>
#include <arch/drivers/sgcn.h>
#include <arch/drivers/kbd.h>
#include <genarch/ofw/ofw_tree.h>
#include <debug.h>
#include <string.h>
#include <print.h>
#include <mm/page.h>
#include <proc/thread.h>
#include <console/chardev.h>
#include <console/console.h>
#include <sysinfo/sysinfo.h>
#include <synch/spinlock.h>

#define POLL_INTERVAL           10000

/*
 * Physical address at which the SBBC starts. This value has been obtained
 * by inspecting (using Simics) memory accesses made by OBP. It is valid
 * for the Simics-simulated Serengeti machine. The author of this code is
 * not sure whether this value is valid generally. 
 */
#define SBBC_START              0x63000000000

/* offset of SRAM within the SBBC memory */
#define SBBC_SRAM_OFFSET        0x900000

/* size (in bytes) of the physical memory area which will be mapped */
#define MAPPED_AREA_SIZE        (128 * 1024)

/* magic string contained at the beginning of SRAM */
#define SRAM_TOC_MAGIC          "TOCSRAM"

/*
 * Key into the SRAM table of contents which identifies the entry
 * describing the OBP console buffer. It is worth mentioning
 * that the OBP console buffer is not the only console buffer
 * which can be used. It is, however, used because when the kernel
 * is running, the OBP buffer is not used by OBP any more but OBP
 * has already made necessary arrangements so that the output will
 * be read from the OBP buffer and input will go to the OBP buffer.
 * Therefore HelenOS needs to make no such arrangements any more.
 */
#define CONSOLE_KEY             "OBPCONS"

/* magic string contained at the beginning of the console buffer */
#define SGCN_BUFFER_MAGIC       "CON"

/*
 * Returns a pointer to the object of a given type which is placed at the given
 * offset from the SRAM beginning.
 */
#define SRAM(type, offset)      ((type *) (sram_begin + (offset)))

/* Returns a pointer to the SRAM table of contents. */
#define SRAM_TOC                (SRAM(iosram_toc_t, 0))

/*
 * Returns a pointer to the object of a given type which is placed at the given
 * offset from the console buffer beginning.
 */
#define SGCN_BUFFER(type, offset) \
        ((type *) (sgcn_buffer_begin + (offset)))

/** Returns a pointer to the console buffer header. */
#define SGCN_BUFFER_HEADER      (SGCN_BUFFER(sgcn_buffer_header_t, 0))

/** defined in drivers/kbd.c */
extern kbd_type_t kbd_type;

/** starting address of SRAM, will be set by the init_sram_begin function */
static uintptr_t sram_begin;

/**
 * starting address of the SGCN buffer, will be set by the
 * init_sgcn_buffer_begin function
 */
static uintptr_t sgcn_buffer_begin;

/* true iff the kernel driver should ignore pressed keys */
static bool kbd_disabled;

/* 
 * Ensures that writing to the buffer and consequent update of the write pointer
 * are together one atomic operation.
 */
SPINLOCK_INITIALIZE(sgcn_output_lock);

/* 
 * Prevents the input buffer read/write pointers from getting to inconsistent
 * state. 
 */
SPINLOCK_INITIALIZE(sgcn_input_lock);


/* functions referenced from definitions of I/O operations structures */
static void sgcn_noop(chardev_t *);
static void sgcn_putchar(chardev_t *, const char, bool);
static char sgcn_key_read(chardev_t *);

/** character device operations */
static chardev_operations_t sgcn_ops = {
        .suspend = sgcn_noop,
        .resume = sgcn_noop,
        .read = sgcn_key_read,
        .write = sgcn_putchar
};

/** SGCN character device */
chardev_t sgcn_io;

/** Address of the chardev, which is connected to SGCN. */
static chardev_t *sgcnout;

/**
 * Set some sysinfo values (SRAM address and SRAM size).
 */
static void register_sram(uintptr_t sram_begin_physical)
{
        sysinfo_set_item_val("sram.area.size", NULL, MAPPED_AREA_SIZE);
        sysinfo_set_item_val("sram.address.physical", NULL,
            sram_begin_physical);
}

/**
 * Initializes the starting address of SRAM.
 *
 * The SRAM starts 0x900000 + C bytes behind the SBBC start in the
 * physical memory, where C is the value read from the "iosram-toc"
 * property of the "/chosen" OBP node. The sram_begin variable will
 * be set to the virtual address which maps to the SRAM physical
 * address.
 */
static void init_sram_begin(void)
{
        ofw_tree_node_t *chosen;
        ofw_tree_property_t *iosram_toc;
        uintptr_t sram_begin_physical;

        chosen = ofw_tree_lookup("/chosen");
        if (!chosen)
                panic("Cannot find '/chosen'.");

        iosram_toc = ofw_tree_getprop(chosen, "iosram-toc");
        if (!iosram_toc)
                panic("Cannot find property 'iosram-toc'.");
        if (!iosram_toc->value)
                panic("Cannot find SRAM TOC.");

        sram_begin_physical = SBBC_START + SBBC_SRAM_OFFSET
            + *((uint32_t *) iosram_toc->value);
        sram_begin = hw_map(sram_begin_physical, MAPPED_AREA_SIZE);
        
        register_sram(sram_begin_physical);
}

/**
 * Initializes the starting address of the SGCN buffer.
 *
 * The offset of the SGCN buffer within SRAM is obtained from the
 * SRAM table of contents. The table of contents contains
 * information about several buffers, among which there is an OBP
 * console buffer - this one will be used as the SGCN buffer. 
 *
 * This function also writes the offset of the SGCN buffer within SRAM
 * under the sram.buffer.offset sysinfo key.
 */
static void sgcn_buffer_begin_init(void)
{
        init_sram_begin();
                
        ASSERT(strcmp(SRAM_TOC->magic, SRAM_TOC_MAGIC) == 0);
        
        /* lookup TOC entry with the correct key */
        uint32_t i;
        for (i = 0; i < MAX_TOC_ENTRIES; i++) {
                if (strcmp(SRAM_TOC->keys[i].key, CONSOLE_KEY) == 0)
                        break;
        }
        ASSERT(i < MAX_TOC_ENTRIES);
        
        sgcn_buffer_begin = sram_begin + SRAM_TOC->keys[i].offset;
        
        sysinfo_set_item_val("sram.buffer.offset", NULL,
            SRAM_TOC->keys[i].offset);
}

/**
 * Default suspend/resume operation for the input device.
 */
static void sgcn_noop(chardev_t *d)
{
}

/**
 * Writes a single character to the SGCN (circular) output buffer
 * and updates the output write pointer so that SGCN gets to know
 * that the character has been written.
 */
static void sgcn_do_putchar(const char c)
{
        uint32_t begin = SGCN_BUFFER_HEADER->out_begin;
        uint32_t end = SGCN_BUFFER_HEADER->out_end;
        uint32_t size = end - begin;
        
        /* we need pointers to volatile variables */
        volatile char *buf_ptr = (volatile char *)
            SGCN_BUFFER(char, SGCN_BUFFER_HEADER->out_wrptr);
        volatile uint32_t *out_wrptr_ptr = &(SGCN_BUFFER_HEADER->out_wrptr);
        volatile uint32_t *out_rdptr_ptr = &(SGCN_BUFFER_HEADER->out_rdptr);

        /*
         * Write the character and increment the write pointer modulo the
         * output buffer size. Note that if we are to rewrite a character
         * which has not been read by the SGCN controller yet (i.e. the output
         * buffer is full), we need to wait until the controller reads some more
         * characters. We wait actively, which means that all threads waiting
         * for the lock are blocked. However, this situation is
         *   1) rare - the output buffer is big, so filling the whole
         *             output buffer is improbable
         *   2) short-lasting - it will take the controller only a fraction
         *             of millisecond to pick the unread characters up
         *   3) not serious - the blocked threads are those that print something
         *             to user console, which is not a time-critical operation
         */
        uint32_t new_wrptr = (((*out_wrptr_ptr) - begin + 1) % size) + begin;
        while (*out_rdptr_ptr == new_wrptr)
                ;
        *buf_ptr = c;
        *out_wrptr_ptr = new_wrptr;
}

/**
 * SGCN output operation. Prints a single character to the SGCN. If the line
 * feed character is written ('\n'), the carriage return character ('\r') is
 * written straight away. 
 */
static void sgcn_putchar(struct chardev * cd, const char c, bool silent)
{
        if (!silent) {
                spinlock_lock(&sgcn_output_lock);
                
                sgcn_do_putchar(c);
                if (c == '\n')
                        sgcn_do_putchar('\r');
                
                spinlock_unlock(&sgcn_output_lock);
        }
}

/**
 * Called when actively reading the character. Not implemented yet.
 */
static char sgcn_key_read(chardev_t *d)
{
        return (char) 0;
}

/**
 * Grabs the input for kernel.
 */
void sgcn_grab(void)
{
        kbd_disabled = true;
}

/**
 * Releases the input so that userspace can use it.
 */
void sgcn_release(void)
{
        kbd_disabled = true;
}

/**
 * Function regularly called by the keyboard polling thread. Finds out whether
 * there are some unread characters in the input queue. If so, it picks them up
 * and sends them to the upper layers of HelenOS.
 */
static void sgcn_poll()
{
        uint32_t begin = SGCN_BUFFER_HEADER->in_begin;
        uint32_t end = SGCN_BUFFER_HEADER->in_end;
        uint32_t size = end - begin;

        if (kbd_disabled)
                return;

        spinlock_lock(&sgcn_input_lock);
        
        /* we need pointers to volatile variables */
        volatile char *buf_ptr = (volatile char *)
            SGCN_BUFFER(char, SGCN_BUFFER_HEADER->in_rdptr);
        volatile uint32_t *in_wrptr_ptr = &(SGCN_BUFFER_HEADER->in_wrptr);
        volatile uint32_t *in_rdptr_ptr = &(SGCN_BUFFER_HEADER->in_rdptr);
        
        while (*in_rdptr_ptr != *in_wrptr_ptr) {
                
                buf_ptr = (volatile char *)
                    SGCN_BUFFER(char, SGCN_BUFFER_HEADER->in_rdptr);
                char c = *buf_ptr;
                *in_rdptr_ptr = (((*in_rdptr_ptr) - begin + 1) % size) + begin;
                        
                if (sgcnout)
                        chardev_push_character(sgcnout, c);     
        }       

        spinlock_unlock(&sgcn_input_lock);
}

/**
 * Polling thread function.
 */
static void kkbdpoll(void *arg) {
        while (1) {
                if (!silent) {
                        sgcn_poll();
                }
                thread_usleep(POLL_INTERVAL);
        }
}

/**
 * A public function which initializes I/O from/to Serengeti console
 * and sets it as a default input/output. 
 */
void sgcn_init(chardev_t *devout)
{
        sgcn_buffer_begin_init();

        kbd_type = KBD_SGCN;

        sysinfo_set_item_val("kbd", NULL, true);
        sysinfo_set_item_val("kbd.type", NULL, KBD_SGCN);
        sysinfo_set_item_val("fb.kind", NULL, 4);

        thread_t *t = thread_create(kkbdpoll, NULL, TASK, 0, "kkbdpoll", true);
        if (!t)
                panic("Cannot create kkbdpoll.");
        thread_ready(t);
        
        chardev_initialize("sgcn_io", &sgcn_io, &sgcn_ops);
        stdout = &sgcn_io;

        sgcnout = devout;
}

/** @}
 */