linux/drivers/mmc/host/owl-mmc.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Actions Semi Owl SoCs SD/MMC driver
 *
 * Copyright (c) 2014 Actions Semi Inc.
 * Copyright (c) 2019 Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
 *
 * TODO: SDIO support
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-direction.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/mmc/host.h>
#include <linux/mmc/slot-gpio.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/reset.h>
#include <linux/spinlock.h>

/*
 * SDC registers
 */
#define OWL_REG_SD_EN			0x0000
#define OWL_REG_SD_CTL			0x0004
#define OWL_REG_SD_STATE		0x0008
#define OWL_REG_SD_CMD			0x000c
#define OWL_REG_SD_ARG			0x0010
#define OWL_REG_SD_RSPBUF0		0x0014
#define OWL_REG_SD_RSPBUF1		0x0018
#define OWL_REG_SD_RSPBUF2		0x001c
#define OWL_REG_SD_RSPBUF3		0x0020
#define OWL_REG_SD_RSPBUF4		0x0024
#define OWL_REG_SD_DAT			0x0028
#define OWL_REG_SD_BLK_SIZE		0x002c
#define OWL_REG_SD_BLK_NUM		0x0030
#define OWL_REG_SD_BUF_SIZE		0x0034

/* SD_EN Bits */
#define OWL_SD_EN_RANE			BIT(31)
#define OWL_SD_EN_RAN_SEED(x)		(((x) & 0x3f) << 24)
#define OWL_SD_EN_S18EN			BIT(12)
#define OWL_SD_EN_RESE			BIT(10)
#define OWL_SD_EN_DAT1_S		BIT(9)
#define OWL_SD_EN_CLK_S			BIT(8)
#define OWL_SD_ENABLE			BIT(7)
#define OWL_SD_EN_BSEL			BIT(6)
#define OWL_SD_EN_SDIOEN		BIT(3)
#define OWL_SD_EN_DDREN			BIT(2)
#define OWL_SD_EN_DATAWID(x)		(((x) & 0x3) << 0)

/* SD_CTL Bits */
#define OWL_SD_CTL_TOUTEN		BIT(31)
#define OWL_SD_CTL_TOUTCNT(x)		(((x) & 0x7f) << 24)
#define OWL_SD_CTL_DELAY_MSK		GENMASK(23, 16)
#define OWL_SD_CTL_RDELAY(x)		(((x) & 0xf) << 20)
#define OWL_SD_CTL_WDELAY(x)		(((x) & 0xf) << 16)
#define OWL_SD_CTL_CMDLEN		BIT(13)
#define OWL_SD_CTL_SCC			BIT(12)
#define OWL_SD_CTL_TCN(x)		(((x) & 0xf) << 8)
#define OWL_SD_CTL_TS			BIT(7)
#define OWL_SD_CTL_LBE			BIT(6)
#define OWL_SD_CTL_C7EN			BIT(5)
#define OWL_SD_CTL_TM(x)		(((x) & 0xf) << 0)

#define OWL_SD_DELAY_LOW_CLK		0x0f
#define OWL_SD_DELAY_MID_CLK		0x0a
#define OWL_SD_DELAY_HIGH_CLK		0x09
#define OWL_SD_RDELAY_DDR50		0x0a
#define OWL_SD_WDELAY_DDR50		0x08

/* SD_STATE Bits */
#define OWL_SD_STATE_DAT1BS		BIT(18)
#define OWL_SD_STATE_SDIOB_P		BIT(17)
#define OWL_SD_STATE_SDIOB_EN		BIT(16)
#define OWL_SD_STATE_TOUTE		BIT(15)
#define OWL_SD_STATE_BAEP		BIT(14)
#define OWL_SD_STATE_MEMRDY		BIT(12)
#define OWL_SD_STATE_CMDS		BIT(11)
#define OWL_SD_STATE_DAT1AS		BIT(10)
#define OWL_SD_STATE_SDIOA_P		BIT(9)
#define OWL_SD_STATE_SDIOA_EN		BIT(8)
#define OWL_SD_STATE_DAT0S		BIT(7)
#define OWL_SD_STATE_TEIE		BIT(6)
#define OWL_SD_STATE_TEI		BIT(5)
#define OWL_SD_STATE_CLNR		BIT(4)
#define OWL_SD_STATE_CLC		BIT(3)
#define OWL_SD_STATE_WC16ER		BIT(2)
#define OWL_SD_STATE_RC16ER		BIT(1)
#define OWL_SD_STATE_CRC7ER		BIT(0)

#define OWL_CMD_TIMEOUT_MS		30000

struct owl_mmc_host {
	struct device *dev;
	struct reset_control *reset;
	void __iomem *base;
	struct clk *clk;
	struct completion sdc_complete;
	spinlock_t lock;
	int irq;
	u32 clock;
	bool ddr_50;

	enum dma_data_direction dma_dir;
	struct dma_chan *dma;
	struct dma_async_tx_descriptor *desc;
	struct dma_slave_config dma_cfg;
	struct completion dma_complete;

	struct mmc_host	*mmc;
	struct mmc_request *mrq;
	struct mmc_command *cmd;
	struct mmc_data	*data;
};

static void owl_mmc_update_reg(void __iomem *reg, unsigned int val, bool state)
{
	unsigned int regval;

	regval = readl(reg);

	if (state)
		regval |= val;
	else
		regval &= ~val;

	writel(regval, reg);
}

static irqreturn_t owl_irq_handler(int irq, void *devid)
{
	struct owl_mmc_host *owl_host = devid;
	u32 state;

	spin_lock(&owl_host->lock);

	state = readl(owl_host->base + OWL_REG_SD_STATE);
	if (state & OWL_SD_STATE_TEI) {
		state = readl(owl_host->base + OWL_REG_SD_STATE);
		state |= OWL_SD_STATE_TEI;
		writel(state, owl_host->base + OWL_REG_SD_STATE);
		complete(&owl_host->sdc_complete);
	}

	spin_unlock(&owl_host->lock);

	return IRQ_HANDLED;
}

static void owl_mmc_finish_request(struct owl_mmc_host *owl_host)
{
	struct mmc_request *mrq = owl_host->mrq;
	struct mmc_data *data = mrq->data;

	/* Should never be NULL */
	WARN_ON(!mrq);

	owl_host->mrq = NULL;

	if (data)
		dma_unmap_sg(owl_host->dma->device->dev, data->sg, data->sg_len,
			     owl_host->dma_dir);

	/* Finally finish request */
	mmc_request_done(owl_host->mmc, mrq);
}

static void owl_mmc_send_cmd(struct owl_mmc_host *owl_host,
			     struct mmc_command *cmd,
			     struct mmc_data *data)
{
	unsigned long timeout;
	u32 mode, state, resp[2];
	u32 cmd_rsp_mask = 0;

	init_completion(&owl_host->sdc_complete);

	switch (mmc_resp_type(cmd)) {
	case MMC_RSP_NONE:
		mode = OWL_SD_CTL_TM(0);
		break;

	case MMC_RSP_R1:
		if (data) {
			if (data->flags & MMC_DATA_READ)
				mode = OWL_SD_CTL_TM(4);
			else
				mode = OWL_SD_CTL_TM(5);
		} else {
			mode = OWL_SD_CTL_TM(1);
		}
		cmd_rsp_mask = OWL_SD_STATE_CLNR | OWL_SD_STATE_CRC7ER;

		break;

	case MMC_RSP_R1B:
		mode = OWL_SD_CTL_TM(3);
		cmd_rsp_mask = OWL_SD_STATE_CLNR | OWL_SD_STATE_CRC7ER;
		break;

	case MMC_RSP_R2:
		mode = OWL_SD_CTL_TM(2);
		cmd_rsp_mask = OWL_SD_STATE_CLNR | OWL_SD_STATE_CRC7ER;
		break;

	case MMC_RSP_R3:
		mode = OWL_SD_CTL_TM(1);
		cmd_rsp_mask = OWL_SD_STATE_CLNR;
		break;

	default:
		dev_warn(owl_host->dev, "Unknown MMC command\n");
		cmd->error = -EINVAL;
		return;
	}

	/* Keep current WDELAY and RDELAY */
	mode |= (readl(owl_host->base + OWL_REG_SD_CTL) & (0xff << 16));

	/* Start to send corresponding command type */
	writel(cmd->arg, owl_host->base + OWL_REG_SD_ARG);
	writel(cmd->opcode, owl_host->base + OWL_REG_SD_CMD);

	/* Set LBE to send clk at the end of last read block */
	if (data) {
		mode |= (OWL_SD_CTL_TS | OWL_SD_CTL_LBE | 0x64000000);
	} else {
		mode &= ~(OWL_SD_CTL_TOUTEN | OWL_SD_CTL_LBE);
		mode |= OWL_SD_CTL_TS;
	}

	owl_host->cmd = cmd;

	/* Start transfer */
	writel(mode, owl_host->base + OWL_REG_SD_CTL);

	if (data)
		return;

	timeout = msecs_to_jiffies(cmd->busy_timeout ? cmd->busy_timeout :
		OWL_CMD_TIMEOUT_MS);

	if (!wait_for_completion_timeout(&owl_host->sdc_complete, timeout)) {
		dev_err(owl_host->dev, "CMD interrupt timeout\n");
		cmd->error = -ETIMEDOUT;
		return;
	}

	state = readl(owl_host->base + OWL_REG_SD_STATE);
	if (mmc_resp_type(cmd) & MMC_RSP_PRESENT) {
		if (cmd_rsp_mask & state) {
			if (state & OWL_SD_STATE_CLNR) {
				dev_err(owl_host->dev, "Error CMD_NO_RSP\n");
				cmd->error = -EILSEQ;
				return;
			}

			if (state & OWL_SD_STATE_CRC7ER) {
				dev_err(owl_host->dev, "Error CMD_RSP_CRC\n");
				cmd->error = -EILSEQ;
				return;
			}
		}

		if (mmc_resp_type(cmd) & MMC_RSP_136) {
			cmd->resp[3] = readl(owl_host->base + OWL_REG_SD_RSPBUF0);
			cmd->resp[2] = readl(owl_host->base + OWL_REG_SD_RSPBUF1);
			cmd->resp[1] = readl(owl_host->base + OWL_REG_SD_RSPBUF2);
			cmd->resp[0] = readl(owl_host->base + OWL_REG_SD_RSPBUF3);
		} else {
			resp[0] = readl(owl_host->base + OWL_REG_SD_RSPBUF0);
			resp[1] = readl(owl_host->base + OWL_REG_SD_RSPBUF1);
			cmd->resp[0] = resp[1] << 24 | resp[0] >> 8;
			cmd->resp[1] = resp[1] >> 8;
		}
	}
}

static void owl_mmc_dma_complete(void *param)
{
	struct owl_mmc_host *owl_host = param;
	struct mmc_data *data = owl_host->data;

	if (data)
		complete(&owl_host->dma_complete);
}

static int owl_mmc_prepare_data(struct owl_mmc_host *owl_host,
				struct mmc_data *data)
{
	u32 total;

	owl_mmc_update_reg(owl_host->base + OWL_REG_SD_EN, OWL_SD_EN_BSEL,
			   true);
	writel(data->blocks, owl_host->base + OWL_REG_SD_BLK_NUM);
	writel(data->blksz, owl_host->base + OWL_REG_SD_BLK_SIZE);
	total = data->blksz * data->blocks;

	if (total < 512)
		writel(total, owl_host->base + OWL_REG_SD_BUF_SIZE);
	else
		writel(512, owl_host->base + OWL_REG_SD_BUF_SIZE);

	if (data->flags & MMC_DATA_WRITE) {
		owl_host->dma_dir = DMA_TO_DEVICE;
		owl_host->dma_cfg.direction = DMA_MEM_TO_DEV;
	} else {
		owl_host->dma_dir = DMA_FROM_DEVICE;
		owl_host->dma_cfg.direction = DMA_DEV_TO_MEM;
	}

	dma_map_sg(owl_host->dma->device->dev, data->sg,
		   data->sg_len, owl_host->dma_dir);

	dmaengine_slave_config(owl_host->dma, &owl_host->dma_cfg);
	owl_host->desc = dmaengine_prep_slave_sg(owl_host->dma, data->sg,
						 data->sg_len,
						 owl_host->dma_cfg.direction,
						 DMA_PREP_INTERRUPT |
						 DMA_CTRL_ACK);
	if (!owl_host->desc) {
		dev_err(owl_host->dev, "Can't prepare slave sg\n");
		return -EBUSY;
	}

	owl_host->data = data;

	owl_host->desc->callback = owl_mmc_dma_complete;
	owl_host->desc->callback_param = (void *)owl_host;
	data->error = 0;

	return 0;
}

static void owl_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
{
	struct owl_mmc_host *owl_host = mmc_priv(mmc);
	struct mmc_data *data = mrq->data;
	int ret;

	owl_host->mrq = mrq;
	if (mrq->data) {
		ret = owl_mmc_prepare_data(owl_host, data);
		if (ret < 0) {
			data->error = ret;
			goto err_out;
		}

		init_completion(&owl_host->dma_complete);
		dmaengine_submit(owl_host->desc);
		dma_async_issue_pending(owl_host->dma);
	}

	owl_mmc_send_cmd(owl_host, mrq->cmd, data);

	if (data) {
		if (!wait_for_completion_timeout(&owl_host->sdc_complete,
						 10 * HZ)) {
			dev_err(owl_host->dev, "CMD interrupt timeout\n");
			mrq->cmd->error = -ETIMEDOUT;
			dmaengine_terminate_all(owl_host->dma);
			goto err_out;
		}

		if (!wait_for_completion_timeout(&owl_host->dma_complete,
						 5 * HZ)) {
			dev_err(owl_host->dev, "DMA interrupt timeout\n");
			mrq->cmd->error = -ETIMEDOUT;
			dmaengine_terminate_all(owl_host->dma);
			goto err_out;
		}

		if (data->stop)
			owl_mmc_send_cmd(owl_host, data->stop, NULL);

		data->bytes_xfered = data->blocks * data->blksz;
	}

err_out:
	owl_mmc_finish_request(owl_host);
}

static int owl_mmc_set_clk_rate(struct owl_mmc_host *owl_host,
				unsigned int rate)
{
	unsigned long clk_rate;
	int ret;
	u32 reg;

	reg = readl(owl_host->base + OWL_REG_SD_CTL);
	reg &= ~OWL_SD_CTL_DELAY_MSK;

	/* Set RDELAY and WDELAY based on the clock */
	if (rate <= 1000000) {
		writel(reg | OWL_SD_CTL_RDELAY(OWL_SD_DELAY_LOW_CLK) |
		       OWL_SD_CTL_WDELAY(OWL_SD_DELAY_LOW_CLK),
		       owl_host->base + OWL_REG_SD_CTL);
	} else if ((rate > 1000000) && (rate <= 26000000)) {
		writel(reg | OWL_SD_CTL_RDELAY(OWL_SD_DELAY_MID_CLK) |
		       OWL_SD_CTL_WDELAY(OWL_SD_DELAY_MID_CLK),
		       owl_host->base + OWL_REG_SD_CTL);
	} else if ((rate > 26000000) && (rate <= 52000000) && !owl_host->ddr_50) {
		writel(reg | OWL_SD_CTL_RDELAY(OWL_SD_DELAY_HIGH_CLK) |
		       OWL_SD_CTL_WDELAY(OWL_SD_DELAY_HIGH_CLK),
		       owl_host->base + OWL_REG_SD_CTL);
	/* DDR50 mode has special delay chain */
	} else if ((rate > 26000000) && (rate <= 52000000) && owl_host->ddr_50) {
		writel(reg | OWL_SD_CTL_RDELAY(OWL_SD_RDELAY_DDR50) |
		       OWL_SD_CTL_WDELAY(OWL_SD_WDELAY_DDR50),
		       owl_host->base + OWL_REG_SD_CTL);
	} else {
		dev_err(owl_host->dev, "SD clock rate not supported\n");
		return -EINVAL;
	}

	clk_rate = clk_round_rate(owl_host->clk, rate << 1);
	ret = clk_set_rate(owl_host->clk, clk_rate);

	return ret;
}

static void owl_mmc_set_clk(struct owl_mmc_host *owl_host, struct mmc_ios *ios)
{
	if (!ios->clock)
		return;

	owl_host->clock = ios->clock;
	owl_mmc_set_clk_rate(owl_host, ios->clock);
}

static void owl_mmc_set_bus_width(struct owl_mmc_host *owl_host,
				  struct mmc_ios *ios)
{
	u32 reg;

	reg = readl(owl_host->base + OWL_REG_SD_EN);
	reg &= ~0x03;
	switch (ios->bus_width) {
	case MMC_BUS_WIDTH_1:
		break;
	case MMC_BUS_WIDTH_4:
		reg |= OWL_SD_EN_DATAWID(1);
		break;
	case MMC_BUS_WIDTH_8:
		reg |= OWL_SD_EN_DATAWID(2);
		break;
	}

	writel(reg, owl_host->base + OWL_REG_SD_EN);
}

static void owl_mmc_ctr_reset(struct owl_mmc_host *owl_host)
{
	reset_control_assert(owl_host->reset);
	udelay(20);
	reset_control_deassert(owl_host->reset);
}

static void owl_mmc_power_on(struct owl_mmc_host *owl_host)
{
	u32 mode;

	init_completion(&owl_host->sdc_complete);

	/* Enable transfer end IRQ */
	owl_mmc_update_reg(owl_host->base + OWL_REG_SD_STATE,
		       OWL_SD_STATE_TEIE, true);

	/* Send init clk */
	mode = (readl(owl_host->base + OWL_REG_SD_CTL) & (0xff << 16));
	mode |= OWL_SD_CTL_TS | OWL_SD_CTL_TCN(5) | OWL_SD_CTL_TM(8);
	writel(mode, owl_host->base + OWL_REG_SD_CTL);

	if (!wait_for_completion_timeout(&owl_host->sdc_complete, HZ)) {
		dev_err(owl_host->dev, "CMD interrupt timeout\n");
		return;
	}
}

static void owl_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
	struct owl_mmc_host *owl_host = mmc_priv(mmc);

	switch (ios->power_mode) {
	case MMC_POWER_UP:
		dev_dbg(owl_host->dev, "Powering card up\n");

		/* Reset the SDC controller to clear all previous states */
		owl_mmc_ctr_reset(owl_host);
		clk_prepare_enable(owl_host->clk);
		writel(OWL_SD_ENABLE | OWL_SD_EN_RESE,
		       owl_host->base + OWL_REG_SD_EN);

		break;

	case MMC_POWER_ON:
		dev_dbg(owl_host->dev, "Powering card on\n");
		owl_mmc_power_on(owl_host);

		break;

	case MMC_POWER_OFF:
		dev_dbg(owl_host->dev, "Powering card off\n");
		clk_disable_unprepare(owl_host->clk);

		return;

	default:
		dev_dbg(owl_host->dev, "Ignoring unknown card power state\n");
		break;
	}

	if (ios->clock != owl_host->clock)
		owl_mmc_set_clk(owl_host, ios);

	owl_mmc_set_bus_width(owl_host, ios);

	/* Enable DDR mode if requested */
	if (ios->timing == MMC_TIMING_UHS_DDR50) {
		owl_host->ddr_50 = true;
		owl_mmc_update_reg(owl_host->base + OWL_REG_SD_EN,
			       OWL_SD_EN_DDREN, true);
	} else {
		owl_host->ddr_50 = false;
	}
}

static int owl_mmc_start_signal_voltage_switch(struct mmc_host *mmc,
					       struct mmc_ios *ios)
{
	struct owl_mmc_host *owl_host = mmc_priv(mmc);

	/* It is enough to change the pad ctrl bit for voltage switch */
	switch (ios->signal_voltage) {
	case MMC_SIGNAL_VOLTAGE_330:
		owl_mmc_update_reg(owl_host->base + OWL_REG_SD_EN,
			       OWL_SD_EN_S18EN, false);
		break;
	case MMC_SIGNAL_VOLTAGE_180:
		owl_mmc_update_reg(owl_host->base + OWL_REG_SD_EN,
			       OWL_SD_EN_S18EN, true);
		break;
	default:
		return -ENOTSUPP;
	}

	return 0;
}

static const struct mmc_host_ops owl_mmc_ops = {
	.request	= owl_mmc_request,
	.set_ios	= owl_mmc_set_ios,
	.get_ro		= mmc_gpio_get_ro,
	.get_cd		= mmc_gpio_get_cd,
	.start_signal_voltage_switch = owl_mmc_start_signal_voltage_switch,
};

static int owl_mmc_probe(struct platform_device *pdev)
{
	struct owl_mmc_host *owl_host;
	struct mmc_host *mmc;
	struct resource *res;
	int ret;

	mmc = mmc_alloc_host(sizeof(struct owl_mmc_host), &pdev->dev);
	if (!mmc) {
		dev_err(&pdev->dev, "mmc alloc host failed\n");
		return -ENOMEM;
	}
	platform_set_drvdata(pdev, mmc);

	owl_host = mmc_priv(mmc);
	owl_host->dev = &pdev->dev;
	owl_host->mmc = mmc;
	spin_lock_init(&owl_host->lock);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	owl_host->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(owl_host->base)) {
		ret = PTR_ERR(owl_host->base);
		goto err_free_host;
	}

	owl_host->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(owl_host->clk)) {
		dev_err(&pdev->dev, "No clock defined\n");
		ret = PTR_ERR(owl_host->clk);
		goto err_free_host;
	}

	owl_host->reset = devm_reset_control_get_exclusive(&pdev->dev, NULL);
	if (IS_ERR(owl_host->reset)) {
		dev_err(&pdev->dev, "Could not get reset control\n");
		ret = PTR_ERR(owl_host->reset);
		goto err_free_host;
	}

	mmc->ops		= &owl_mmc_ops;
	mmc->max_blk_count	= 512;
	mmc->max_blk_size	= 512;
	mmc->max_segs		= 256;
	mmc->max_seg_size	= 262144;
	mmc->max_req_size	= 262144;
	/* 100kHz ~ 52MHz */
	mmc->f_min		= 100000;
	mmc->f_max		= 52000000;
	mmc->caps	       |= MMC_CAP_MMC_HIGHSPEED | MMC_CAP_SD_HIGHSPEED |
				  MMC_CAP_4_BIT_DATA;
	mmc->caps2		= (MMC_CAP2_BOOTPART_NOACC | MMC_CAP2_NO_SDIO);
	mmc->ocr_avail		= MMC_VDD_32_33 | MMC_VDD_33_34 |
				  MMC_VDD_165_195;

	ret = mmc_of_parse(mmc);
	if (ret)
		goto err_free_host;

	pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
	pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
	owl_host->dma = dma_request_chan(&pdev->dev, "mmc");
	if (IS_ERR(owl_host->dma)) {
		dev_err(owl_host->dev, "Failed to get external DMA channel.\n");
		ret = PTR_ERR(owl_host->dma);
		goto err_free_host;
	}

	dev_info(&pdev->dev, "Using %s for DMA transfers\n",
		 dma_chan_name(owl_host->dma));

	owl_host->dma_cfg.src_addr = res->start + OWL_REG_SD_DAT;
	owl_host->dma_cfg.dst_addr = res->start + OWL_REG_SD_DAT;
	owl_host->dma_cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
	owl_host->dma_cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
	owl_host->dma_cfg.device_fc = false;

	owl_host->irq = platform_get_irq(pdev, 0);
	if (owl_host->irq < 0) {
		ret = -EINVAL;
		goto err_release_channel;
	}

	ret = devm_request_irq(&pdev->dev, owl_host->irq, owl_irq_handler,
			       0, dev_name(&pdev->dev), owl_host);
	if (ret) {
		dev_err(&pdev->dev, "Failed to request irq %d\n",
			owl_host->irq);
		goto err_release_channel;
	}

	ret = mmc_add_host(mmc);
	if (ret) {
		dev_err(&pdev->dev, "Failed to add host\n");
		goto err_release_channel;
	}

	dev_dbg(&pdev->dev, "Owl MMC Controller Initialized\n");

	return 0;

err_release_channel:
	dma_release_channel(owl_host->dma);
err_free_host:
	mmc_free_host(mmc);

	return ret;
}

static int owl_mmc_remove(struct platform_device *pdev)
{
	struct mmc_host	*mmc = platform_get_drvdata(pdev);
	struct owl_mmc_host *owl_host = mmc_priv(mmc);

	mmc_remove_host(mmc);
	disable_irq(owl_host->irq);
	dma_release_channel(owl_host->dma);
	mmc_free_host(mmc);

	return 0;
}

static const struct of_device_id owl_mmc_of_match[] = {
	{.compatible = "actions,owl-mmc",},
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, owl_mmc_of_match);

static struct platform_driver owl_mmc_driver = {
	.driver = {
		.name	= "owl_mmc",
		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
		.of_match_table = owl_mmc_of_match,
	},
	.probe		= owl_mmc_probe,
	.remove		= owl_mmc_remove,
};
module_platform_driver(owl_mmc_driver);

MODULE_DESCRIPTION("Actions Semi Owl SoCs SD/MMC Driver");
MODULE_AUTHOR("Actions Semi");
MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
MODULE_LICENSE("GPL");