xref: /openbmc/linux/drivers/gpu/drm/radeon/atombios_i2c.c (revision 831719d62f692e28699a7acd7b441c6f0c01b6f7)

/*
 * Copyright 2011 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: Alex Deucher
 *
 */
#include <drm/drmP.h>
#include <drm/radeon_drm.h>
#include "radeon.h"
#include "atom.h"

#define TARGET_HW_I2C_CLOCK 50

/* these are a limitation of ProcessI2cChannelTransaction not the hw */
#define ATOM_MAX_HW_I2C_WRITE 3
#define ATOM_MAX_HW_I2C_READ  255

static int radeon_process_i2c_ch(struct radeon_i2c_chan *chan,
				 u8 slave_addr, u8 flags,
				 u8 *buf, u8 num)
{
	struct drm_device *dev = chan->dev;
	struct radeon_device *rdev = dev->dev_private;
	PROCESS_I2C_CHANNEL_TRANSACTION_PS_ALLOCATION args;
	int index = GetIndexIntoMasterTable(COMMAND, ProcessI2cChannelTransaction);
	unsigned char *base;
	u16 out = cpu_to_le16(0);
	int r = 0;

	memset(&args, 0, sizeof(args));

	mutex_lock(&chan->mutex);

	base = (unsigned char *)rdev->mode_info.atom_context->scratch;

	if (flags & HW_I2C_WRITE) {
		if (num > ATOM_MAX_HW_I2C_WRITE) {
			DRM_ERROR("hw i2c: tried to write too many bytes (%d vs 3)\n", num);
			r = -EINVAL;
			goto done;
		}
		if (buf == NULL)
			args.ucRegIndex = 0;
		else
			args.ucRegIndex = buf[0];
		if (num)
			num--;
		if (num)
			memcpy(&out, &buf[1], num);
		args.lpI2CDataOut = cpu_to_le16(out);
	} else {
		if (num > ATOM_MAX_HW_I2C_READ) {
			DRM_ERROR("hw i2c: tried to read too many bytes (%d vs 255)\n", num);
			r = -EINVAL;
			goto done;
		}
		args.ucRegIndex = 0;
		args.lpI2CDataOut = 0;
	}

	args.ucFlag = flags;
	args.ucI2CSpeed = TARGET_HW_I2C_CLOCK;
	args.ucTransBytes = num;
	args.ucSlaveAddr = slave_addr << 1;
	args.ucLineNumber = chan->rec.i2c_id;

	atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);

	/* error */
	if (args.ucStatus != HW_ASSISTED_I2C_STATUS_SUCCESS) {
		DRM_DEBUG_KMS("hw_i2c error\n");
		r = -EIO;
		goto done;
	}

	if (!(flags & HW_I2C_WRITE))
		radeon_atom_copy_swap(buf, base, num, false);

done:
	mutex_unlock(&chan->mutex);

	return r;
}

int radeon_atom_hw_i2c_xfer(struct i2c_adapter *i2c_adap,
			    struct i2c_msg *msgs, int num)
{
	struct radeon_i2c_chan *i2c = i2c_get_adapdata(i2c_adap);
	struct i2c_msg *p;
	int i, remaining, current_count, buffer_offset, max_bytes, ret;
	u8 flags;

	/* check for bus probe */
	p = &msgs[0];
	if ((num == 1) && (p->len == 0)) {
		ret = radeon_process_i2c_ch(i2c,
					    p->addr, HW_I2C_WRITE,
					    NULL, 0);
		if (ret)
			return ret;
		else
			return num;
	}

	for (i = 0; i < num; i++) {
		p = &msgs[i];
		remaining = p->len;
		buffer_offset = 0;
		/* max_bytes are a limitation of ProcessI2cChannelTransaction not the hw */
		if (p->flags & I2C_M_RD) {
			max_bytes = ATOM_MAX_HW_I2C_READ;
			flags = HW_I2C_READ;
		} else {
			max_bytes = ATOM_MAX_HW_I2C_WRITE;
			flags = HW_I2C_WRITE;
		}
		while (remaining) {
			if (remaining > max_bytes)
				current_count = max_bytes;
			else
				current_count = remaining;
			ret = radeon_process_i2c_ch(i2c,
						    p->addr, flags,
						    &p->buf[buffer_offset], current_count);
			if (ret)
				return ret;
			remaining -= current_count;
			buffer_offset += current_count;
		}
	}

	return num;
}

u32 radeon_atom_hw_i2c_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}