Subject: [PATCH v2 2/2] MMC: meson: initial support for GXBB platforms

From: [email-masked] (Stephen Boyd)
Date: Mon, 22 Aug 2016 18:21:24 -0700

On 08/03, Kevin Hilman wrote:
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7304d2e37a98..3762e46811f3 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -972,6 +972,7 @@ F:	arch/arm/mach-meson/
>  F:	arch/arm/boot/dts/meson*
>  F:	arch/arm64/boot/dts/amlogic/
>  F: 	drivers/pinctrl/meson/
> +F:      drivers/mmc/host/meson*

Weird spacing here?

>  N:	meson
>  
>  ARM/Annapurna Labs ALPINE ARCHITECTURE
> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> index 0aa484c10c0a..4c3d091f7548 100644
> --- a/drivers/mmc/host/Kconfig
> +++ b/drivers/mmc/host/Kconfig
> @@ -332,6 +332,16 @@ config MMC_SDHCI_IPROC
>  
>  	  If unsure, say N.
>  
> +config MMC_MESON_GXBB
> +	tristate "Amlogic S905/GXBB SD/MMC Host Controller support"
> +	depends on ARCH_MESON && MMC
> +	help
> +	  This selects support for the Amlogic SD/MMC Host Controller
> +	  found on the S905/GXBB family of SoCs.  This controller is
> +	  MMC 5.1 compliant and support SD, eMMC and SDIO interfaces.

s/support/supports/

> +
> +	  If you have a controller with this interface, say Y here.
> +
>  config MMC_MOXART
>  	tristate "MOXART SD/MMC Host Controller support"
>  	depends on ARCH_MOXART && MMC
> diff --git a/drivers/mmc/host/meson-gxbb.c b/drivers/mmc/host/meson-gxbb.c
> new file mode 100644
> index 000000000000..10eac41cf31a
> --- /dev/null
> +++ b/drivers/mmc/host/meson-gxbb.c
> @@ -0,0 +1,918 @@
> +/*
> + * This file is provided under a dual BSD/GPLv2 license.  When using or
> + * redistributing this file, you may do so under either license.
> + *
> + * GPL LICENSE SUMMARY
> + *
> + * Copyright (c) 2016 BayLibre, SAS.
> + * Author: Kevin Hilman <[email-masked]>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of version 2 of the GNU General Public License as
> + * published by the Free Software Foundation.
> + *
> + * 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/>.
> + * The full GNU General Public License is included in this distribution
> + * in the file called COPYING.
> + *
> + * BSD LICENSE
> + *
> + * Copyright (c) 2016 BayLibre, SAS.
> + * Author: Kevin Hilman <[email-masked]>
> + *
> + * 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.
> + *   * Neither the name of Intel Corporation nor the names of its
> + *     contributors may be used to endorse or promote products derived
> + *     from this software without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> + * "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 COPYRIGHT
> + * OWNER OR CONTRIBUTORS 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.
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>

Unused?

> +#include <linux/init.h>
> +#include <linux/device.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/ioport.h>
> +#include <linux/regmap.h>

Unused?

> +#include <linux/spinlock.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/mmc/host.h>
> +#include <linux/mmc/mmc.h>
> +#include <linux/mmc/sdio.h>
> +#include <linux/mmc/slot-gpio.h>
> +#include <linux/io.h>
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +
> +#define DRIVER_NAME "meson-gxbb-mmc"
> +
> +#define SD_EMMC_CLOCK 0x0
> +#define   CLK_DIV_SHIFT 0
> +#define   CLK_DIV_WIDTH 6
> +#define   CLK_DIV_MASK 0x3f
> +#define   CLK_DIV_MAX 63
> +#define   CLK_SRC_SHIFT 6
> +#define   CLK_SRC_WIDTH 2
> +#define   CLK_SRC_MASK 0x3
> +#define   CLK_SRC_XTAL 0   /* external crystal */
> +#define   CLK_SRC_XTAL_RATE 24000000
> +#define   CLK_SRC_PLL 1    /* FCLK_DIV2 */
> +#define   CLK_SRC_PLL_RATE 1000000000
> +#define   CLK_PHASE_SHIFT 8
> +#define   CLK_PHASE_MASK 0x3
> +#define   CLK_PHASE_0 0
> +#define   CLK_PHASE_90 1
> +#define   CLK_PHASE_180 2
> +#define   CLK_PHASE_270 3
> +#define   CLK_ALWAYS_ON BIT(24)
> +
> +#define SD_EMMC_DElAY 0x4
> +#define SD_EMMC_ADJUST 0x8
> +#define SD_EMMC_CALOUT 0x10
> +#define SD_EMMC_START 0x40
> +#define   START_DESC_INIT BIT(0)
> +#define   START_DESC_BUSY BIT(1)
> +#define   START_DESC_ADDR_SHIFT 2
> +#define   START_DESC_ADDR_MASK (~0x3)
> +
> +#define SD_EMMC_CFG 0x44
> +#define   CFG_BUS_WIDTH_SHIFT 0
> +#define   CFG_BUS_WIDTH_MASK 0x3
> +#define   CFG_BUS_WIDTH_1 0x0
> +#define   CFG_BUS_WIDTH_4 0x1
> +#define   CFG_BUS_WIDTH_8 0x2
> +#define   CFG_DDR BIT(2)
> +#define   CFG_BLK_LEN_SHIFT 4
> +#define   CFG_BLK_LEN_MASK 0xf
> +#define   CFG_RESP_TIMEOUT_SHIFT 8
> +#define   CFG_RESP_TIMEOUT_MASK 0xf
> +#define   CFG_RC_CC_SHIFT 12
> +#define   CFG_RC_CC_MASK 0xf
> +#define   CFG_STOP_CLOCK BIT(22)
> +#define   CFG_CLK_ALWAYS_ON BIT(18)
> +#define   CFG_AUTO_CLK BIT(23)
> +
> +#define SD_EMMC_STATUS 0x48
> +#define   STATUS_BUSY BIT(31)
> +
> +#define SD_EMMC_IRQ_EN 0x4c
> +#define   IRQ_EN_MASK 0x3fff
> +#define   IRQ_RXD_ERR_SHIFT 0
> +#define   IRQ_RXD_ERR_MASK 0xff
> +#define   IRQ_TXD_ERR BIT(8)
> +#define   IRQ_DESC_ERR BIT(9)
> +#define   IRQ_RESP_ERR BIT(10)
> +#define   IRQ_RESP_TIMEOUT BIT(11)
> +#define   IRQ_DESC_TIMEOUT BIT(12)
> +#define   IRQ_END_OF_CHAIN BIT(13)
> +#define   IRQ_RESP_STATUS BIT(14)
> +#define   IRQ_SDIO BIT(15)
> +
> +#define SD_EMMC_CMD_CFG 0x50
> +#define SD_EMMC_CMD_ARG 0x54
> +#define SD_EMMC_CMD_DAT 0x58
> +#define SD_EMMC_CMD_RSP 0x5c
> +#define SD_EMMC_CMD_RSP1 0x60
> +#define SD_EMMC_CMD_RSP2 0x64
> +#define SD_EMMC_CMD_RSP3 0x68
> +
> +#define SD_EMMC_RXD 0x94
> +#define SD_EMMC_TXD 0x94
> +#define SD_EMMC_LAST_REG SD_EMMC_TXD
> +
> +#define SD_EMMC_CFG_BLK_SIZE 512 /* internal buffer max: 512 bytes */
> +#define SD_EMMC_CFG_RESP_TIMEOUT 256 /* in clock cycles */
> +#define SD_EMMC_CFG_CMD_GAP 16 /* in clock cycles */
> +#define MUX_CLK_NUM_PARENTS 2
> +
> +struct meson_host {
> +	struct	device		*dev;
> +	struct	mmc_host	*mmc;
> +	struct	mmc_request	*mrq;
> +	struct	mmc_command	*cmd;
> +
> +	spinlock_t lock;
> +	void __iomem *regs;
> +#ifdef USE_REGMAP
> +	struct regmap *regmap;
> +#endif

Dead code?

> +	int irq;
> +	u32 ocr_mask;
> +	struct clk *core_clk;
> +	struct clk_mux mux;
> +	struct clk *mux_clk;
> +	struct clk *mux_parent[MUX_CLK_NUM_PARENTS];
> +	unsigned long mux_parent_rate[MUX_CLK_NUM_PARENTS];
> +
> +	struct clk_divider cfg_div;
> +	struct clk *cfg_div_clk;
> +
> +	unsigned int bounce_buf_size;
> +	void *bounce_buf;
> +	dma_addr_t bounce_dma_addr;
> +
> +	unsigned long clk_rate;
> +	unsigned long clk_src_rate;
> +	unsigned short clk_src_div;
> +};
> +
> +#define reg_read(host, offset) readl(host->regs + offset)
> +#define reg_write(host, offset, val) writel(val, host->regs + offset)
> +
> +struct cmd_cfg {
> +	union {
> +		struct {
> +			u32 length:9;
> +			u32 block_mode:1;
> +			u32 r1b:1;
> +			u32 end_of_chain:1;
> +			u32 timeout:4; /* 2^timeout msec */
> +			u32 no_resp:1;
> +			u32 no_cmd:1;
> +			u32 data_io:1;
> +			u32 data_wr:1;
> +			u32 resp_nocrc:1;
> +			u32 resp_128:1;
> +			u32 resp_num:1;
> +			u32 data_num:1;
> +			u32 cmd_index:6;
> +			u32 error:1;
> +			u32 owner:1;

> +#define CFG_OWNER_CPU 1
> +#define CFG_OWNER_MMC 0
> +		};
> +		u32 val;

Does this need to be __le32 to handle endian swaps? I thought
bitfields weren't safe for things that are written to hardware,
but I can't seem to find any definitive email about that
anywhere.

> +	};
> +};
> +
> +struct sd_emmc_desc {
> +	struct cmd_cfg cmd_cfg;
> +	u32 cmd_arg;
> +	u32 cmd_data;
> +	u32 cmd_resp;

__le32?

> +};
> +#define CMD_DATA_MASK (~0x3)
> +#define CMD_DATA_BIG_ENDIAN BIT(1)
> +#define CMD_DATA_SRAM BIT(0)
> +#define CMD_RESP_MASK (~0x1)
> +#define CMD_RESP_SRAM BIT(0)
> +
> +static int meson_mmc_clk_set(struct meson_host *host, unsigned long clk_rate)
> +{
> +	struct mmc_host *mmc = host->mmc;
> +	int ret = 0;
> +	u32 cfg;
> +
> +	if (clk_rate) {
> +		if (WARN_ON(clk_rate > mmc->f_max))
> +			clk_rate = mmc->f_max;
> +		else if (WARN_ON(clk_rate < mmc->f_min))
> +			clk_rate = mmc->f_min;
> +	}
> +
> +	if (clk_rate == host->clk_rate)
> +		return 0;
> +
> +	/* stop clock */
> +	cfg = reg_read(host, SD_EMMC_CFG);
> +	if (!(cfg & CFG_STOP_CLOCK)) {
> +		cfg |= CFG_STOP_CLOCK;
> +		reg_write(host, SD_EMMC_CFG, cfg);
> +	}
> +
> +	dev_dbg(host->dev, "change clock rate %lu -> %lu\n",
> +		host->clk_rate, clk_rate);
> +	ret = clk_set_rate(host->cfg_div_clk, clk_rate);
> +	if (clk_rate && clk_rate != clk_get_rate(host->cfg_div_clk))
> +		dev_warn(host->dev, "divider requested rate %lu != actual rate %lu: ret=%d\n",
> +			 clk_rate, clk_get_rate(host->cfg_div_clk), ret);
> +	else
> +		host->clk_rate = clk_rate;
> +
> +	/* (re)start clock, if non-zero */
> +	if (clk_rate) {
> +		cfg = reg_read(host, SD_EMMC_CFG);
> +		cfg &= ~CFG_STOP_CLOCK;
> +		reg_write(host, SD_EMMC_CFG, cfg);
> +	}
> +
> +	return ret;
> +}
> +
> +static int meson_mmc_clk_init(struct meson_host *host)
> +{
> +	struct clk_init_data init;
> +	char clk_name[32];
> +	int i, ret = 0;
> +	const char *mux_parent_names[MUX_CLK_NUM_PARENTS];
> +	unsigned int mux_parent_count = 0;
> +	const char *clk_div_parents[1];
> +	unsigned int f_min = UINT_MAX;
> +	u32 clk_reg, cfg;
> +
> +	/* get the mux parents from DT */

None of this looks DT specific (good).

> +	for (i = 0; i < MUX_CLK_NUM_PARENTS; i++) {
> +		char name[16];
> +
> +		snprintf(name, sizeof(name), "clkin%d", i);
> +		host->mux_parent[i] = devm_clk_get(host->dev, name);
> +		if (IS_ERR(host->mux_parent[i])) {
> +			ret = PTR_ERR(host->mux_parent[i]);
> +			if (PTR_ERR(host->mux_parent[i]) != -EPROBE_DEFER)
> +				dev_err(host->dev, "Missing clock %s\n", name);
> +			host->mux_parent[i] = NULL;
> +			return ret;
> +		}
> +
> +		host->mux_parent_rate[i] = clk_get_rate(host->mux_parent[i]);
> +		mux_parent_names[i] = __clk_get_name(host->mux_parent[i]);
> +		mux_parent_count++;
> +		if (host->mux_parent_rate[i] < f_min)
> +			f_min = host->mux_parent_rate[i];
> +	}
> +
> +	/* cacluate f_min based on input clocks, and max divider value */
> +	if (f_min != UINT_MAX)
> +		f_min = DIV_ROUND_UP(CLK_SRC_XTAL_RATE, CLK_DIV_MAX);
> +	else
> +		f_min = 4000000;  /* default min: 400 MHz */
> +	host->mmc->f_min = f_min;
> +
> +	/* create the mux */
> +	snprintf(clk_name, sizeof(clk_name), "%s#mux", dev_name(host->dev));
> +	init.name = clk_name;
> +	init.ops = &clk_mux_ops;
> +	init.flags = CLK_IS_BASIC;

Do you need CLK_IS_BASIC? If not please drop it.

> +	init.parent_names = mux_parent_names;
> +	init.num_parents = mux_parent_count;
> +
> +	host->mux.reg = host->regs + SD_EMMC_CLOCK;
> +	host->mux.shift = CLK_SRC_SHIFT;
> +	host->mux.mask = CLK_SRC_MASK;
> +	host->mux.flags = 0;
> +	host->mux.table = NULL;
> +	host->mux.hw.init = &init;
> +
> +	host->mux_clk = devm_clk_register(host->dev, &host->mux.hw);

Hmm I was hoping to get rid of devm_clk_register() and replace it
with devm_clk_hw_register() instead. All part of my grand plan to
split providers from consumers, but this driver is different in
the sense that it registers clks to provide to itself. Maybe we
should make __clk_create_clk() into a real clk provider API so
that we can use devm_clk_hw_register() here and then generate a
clk for this device from the hw structure.

> +	if (WARN_ON(PTR_ERR_OR_ZERO(host->mux_clk)))

NULL is a valid clk so I would expect to only see
WARN_ON(IS_ERR(host->mux_clk)) here.

> +		return PTR_ERR(host->mux_clk);
> +
> +	/* create the divider */
> +	snprintf(clk_name, sizeof(clk_name), "%s#div", dev_name(host->dev));
> +	init.name = devm_kstrdup(host->dev, clk_name, GFP_KERNEL);
> +	init.ops = &clk_divider_ops;
> +	init.flags = CLK_IS_BASIC | CLK_SET_RATE_PARENT;
> +	clk_div_parents[0] = __clk_get_name(host->mux_clk);
> +	init.parent_names = clk_div_parents;
> +	init.num_parents = ARRAY_SIZE(clk_div_parents);
> +
> +	host->cfg_div.reg = host->regs + SD_EMMC_CLOCK;
> +	host->cfg_div.shift = CLK_DIV_SHIFT;
> +	host->cfg_div.width = CLK_DIV_WIDTH;
> +	host->cfg_div.hw.init = &init;
> +	host->cfg_div.flags = CLK_DIVIDER_ONE_BASED |
> +		CLK_DIVIDER_ROUND_CLOSEST | CLK_DIVIDER_ALLOW_ZERO;
> +
> +	host->cfg_div_clk = devm_clk_register(host->dev, &host->cfg_div.hw);
> +	if (WARN_ON(PTR_ERR_OR_ZERO(host->cfg_div_clk)))
> +		return PTR_ERR(host->cfg_div_clk);
> +
> +	/* init SD_EMMC_CLOCK to sane defaults w/min clock rate */
> +	clk_reg = 0;
> +	clk_reg |= CLK_PHASE_180 << CLK_PHASE_SHIFT;
> +	clk_reg |= CLK_SRC_XTAL << CLK_SRC_SHIFT;
> +	clk_reg |= CLK_DIV_MAX << CLK_DIV_SHIFT;
> +	clk_reg &= ~CLK_ALWAYS_ON;
> +	reg_write(host, SD_EMMC_CLOCK, clk_reg);
> +
> +	clk_prepare_enable(host->cfg_div_clk);

This can fail...

> +
> +	/* Ensure clock starts in "auto" mode, not "always on" */
> +	cfg = reg_read(host, SD_EMMC_CFG);
> +	cfg &= ~CFG_CLK_ALWAYS_ON;
> +	cfg |= CFG_AUTO_CLK;
> +	reg_write(host, SD_EMMC_CFG, cfg);
> +
> +	meson_mmc_clk_set(host, f_min);

This can fail too but we don't handle the error?

> +
> +	return ret;
> +}
> +
> +static void meson_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> +{
> +	struct meson_host *host = mmc_priv(mmc);
> +	u32 bus_width;
> +	u32 val, orig;
> +
> +	/*
> +	 * GPIO regulator, only controls switching between 1v8 and
> +	 * 3v3, doesn't support MMC_POWER_OFF, MMC_POWER_ON.
> +	 */
> +	switch (ios->power_mode) {
> +	case MMC_POWER_UP:
> +		if (!IS_ERR(mmc->supply.vmmc))
> +			mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, ios->vdd);
> +	}
> +
> +	meson_mmc_clk_set(host, ios->clock);
> +
> +	/* Bus width */
> +	val = reg_read(host, SD_EMMC_CFG);
> +	switch (ios->bus_width) {
> +	case MMC_BUS_WIDTH_1:
> +		bus_width = CFG_BUS_WIDTH_1;
> +		break;
> +	case MMC_BUS_WIDTH_4:
> +		bus_width = CFG_BUS_WIDTH_4;
> +		break;
> +	case MMC_BUS_WIDTH_8:
> +		bus_width = CFG_BUS_WIDTH_8;
> +		break;
> +	default:
> +		dev_err(host->dev, "Invalid ios->bus_width: %u.  Setting to 4.\n",
> +			ios->bus_width);
> +		bus_width = CFG_BUS_WIDTH_4;
> +		return;
> +	}
> +
> +	val = reg_read(host, SD_EMMC_CFG);
> +	orig = val;
> +
> +	val &= ~(CFG_BUS_WIDTH_MASK << CFG_BUS_WIDTH_SHIFT);
> +	val |= bus_width << CFG_BUS_WIDTH_SHIFT;
> +
> +	val &= ~(CFG_BLK_LEN_MASK << CFG_BLK_LEN_SHIFT);
> +	val |= ilog2(SD_EMMC_CFG_BLK_SIZE) << CFG_BLK_LEN_SHIFT;
> +
> +	val &= ~(CFG_RESP_TIMEOUT_MASK << CFG_RESP_TIMEOUT_SHIFT);
> +	val |= ilog2(SD_EMMC_CFG_RESP_TIMEOUT) << CFG_RESP_TIMEOUT_SHIFT;
> +
> +	val &= ~(CFG_RC_CC_MASK << CFG_RC_CC_SHIFT);
> +	val |= ilog2(SD_EMMC_CFG_CMD_GAP) << CFG_RC_CC_SHIFT;
> +
> +	reg_write(host, SD_EMMC_CFG, val);
> +
> +	if (val != orig)
> +		dev_dbg(host->dev, "%s: SD_EMMC_CFG: 0x%08x -> 0x%08x\n",
> +			__func__, orig, val);
> +}
> +
> +static int meson_mmc_wait_busy(struct mmc_host *mmc, unsigned int timeout)
> +{
> +	struct meson_host *host = mmc_priv(mmc);
> +	u32 status;
> +	int i;
> +
> +	for (i = timeout; i > 0; i--) {
> +		status = reg_read(host, SD_EMMC_STATUS);
> +		if (!(status & STATUS_BUSY))
> +			break;
> +	};
> +
> +	return (timeout == 0);
> +}
> +
> +static int meson_mmc_request_done(struct mmc_host *mmc, struct mmc_request *mrq)
> +{
> +	struct meson_host *host = mmc_priv(mmc);
> +	struct mmc_command *cmd = host->cmd;
> +	unsigned int loops = 0xfffff;

Perhaps this should be a value of time instead of raw loops? Who
knows how fast the CPU can run all those loops?

> +
> +	WARN_ON(host->mrq != mrq);
> +	if (cmd && !cmd->error)
> +		if (meson_mmc_wait_busy(mmc, loops))
> +			dev_warn(host->dev, "%s: timeout busy.\n", __func__);
> +
> +	host->mrq = NULL;
> +	host->cmd = NULL;
> +	mmc_request_done(host->mmc, mrq);
> +
> +	return 0;
> +}
> +
[...]
> +
> +static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
> +{
> +	struct meson_host *host = mmc_priv(mmc);
> +
> +	WARN_ON(host->mrq != NULL);
> +
> +	/* Stop execution */
> +	reg_write(host, SD_EMMC_START, 0);
> +
> +	/* clear, ack, enable all interrupts */
> +	reg_write(host, SD_EMMC_IRQ_EN, 0);
> +	reg_write(host, SD_EMMC_STATUS, IRQ_EN_MASK);
> +	reg_write(host, SD_EMMC_IRQ_EN, IRQ_EN_MASK);
> +
> +	host->mrq = mrq;
> +
> +	if (meson_mmc_check_cmd(mmc, mrq->cmd))
> +		return;
> +
> +	if (mrq->sbc)
> +		meson_mmc_start_cmd(mmc, mrq->sbc);
> +	else
> +		meson_mmc_start_cmd(mmc, mrq->cmd);
> +}
> +
> +static int meson_mmc_read_resp(struct mmc_host *mmc, struct mmc_command *cmd)
> +{
> +	struct meson_host *host = mmc_priv(mmc);
> +
> +	if (!cmd) {

This happens? 

> +		dev_dbg(host->dev, "%s: NULL command.\n", __func__);
> +		return -EINVAL;
> +	}
> +
> +	if (cmd->flags & MMC_RSP_136) {
> +		cmd->resp[0] = reg_read(host, SD_EMMC_CMD_RSP3);
> +		cmd->resp[1] = reg_read(host, SD_EMMC_CMD_RSP2);
> +		cmd->resp[2] = reg_read(host, SD_EMMC_CMD_RSP1);
> +		cmd->resp[3] = reg_read(host, SD_EMMC_CMD_RSP);
> +	} else if (cmd->flags & MMC_RSP_PRESENT) {
> +		cmd->resp[0] = reg_read(host, SD_EMMC_CMD_RSP);
> +	}
> +
> +	return 0;
> +}
> +
> +static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
> +{
> +	struct meson_host *host = dev_id;
> +	struct mmc_request *mrq = host->mrq;
> +	struct mmc_command *cmd = host->cmd;
> +	u32 irq_en, status, raw_status;
> +	irqreturn_t ret = IRQ_HANDLED;
> +
> +	if (WARN_ON(!host))
> +		return IRQ_NONE;
> +
> +	if (WARN_ON(!mrq))
> +		return IRQ_NONE;
> +
> +	if (WARN_ON(!cmd))
> +		return IRQ_NONE;

These can happen? Spurious interrupts abound? Ugh.

> +
> +	spin_lock(&host->lock);
> +	irq_en = reg_read(host, SD_EMMC_IRQ_EN);
> +	raw_status = reg_read(host, SD_EMMC_STATUS);
> +	status = raw_status & irq_en;
> +
> +	if (!status) {
> +		dev_warn(host->dev, "Spurious IRQ! status=0x%08x, irq_en=0x%08x\n",
> +			 raw_status, irq_en);
> +		ret = IRQ_NONE;
> +		goto out;
> +	}
> +
> +	cmd->error = 0;
> +	if (status & IRQ_RXD_ERR_MASK) {
> +		dev_dbg(host->dev, "Unhandled IRQ: RXD error\n");
> +		cmd->error = -EILSEQ;
> +	}
> +	if (status & IRQ_TXD_ERR) {
> +		dev_dbg(host->dev, "Unhandled IRQ: TXD error\n");
> +		cmd->error = -EILSEQ;
> +	}
> +	if (status & IRQ_DESC_ERR)
> +		dev_dbg(host->dev, "Unhandled IRQ: Descriptor error\n");
> +	if (status & IRQ_RESP_ERR) {
> +		dev_dbg(host->dev, "Unhandled IRQ: Response error\n");
> +		cmd->error = -EILSEQ;
> +	}
> +	if (status & IRQ_RESP_TIMEOUT) {
> +		dev_dbg(host->dev, "Unhandled IRQ: Response timeout\n");
> +		cmd->error = -ETIMEDOUT;
> +	}
> +	if (status & IRQ_DESC_TIMEOUT) {
> +		dev_dbg(host->dev, "Unhandled IRQ: Descriptor timeout\n");
> +		cmd->error = -ETIMEDOUT;
> +	}
> +	if (status & IRQ_SDIO)
> +		dev_dbg(host->dev, "Unhandled IRQ: SDIO.\n");
> +
> +	if (status & (IRQ_END_OF_CHAIN | IRQ_RESP_STATUS))
> +		ret = IRQ_WAKE_THREAD;
> +	else  {
> +		dev_warn(host->dev, "Unknown IRQ! status=0x%04x: MMC CMD%u arg=0x%08x flags=0x%08x stop=%d\n",
> +			 status, cmd->opcode, cmd->arg,
> +			 cmd->flags, mrq->stop ? 1 : 0);
> +		if (cmd->data) {
> +			struct mmc_data *data = cmd->data;
> +
> +			dev_warn(host->dev, "\tblksz %u blocks %u flags 0x%08x (%s%s)",
> +				 data->blksz, data->blocks, data->flags,
> +				 data->flags & MMC_DATA_WRITE ? "write" : "",
> +				 data->flags & MMC_DATA_READ ? "read" : "");
> +		}
> +	}
> +
> +out:
> +	/* ack all (enabled) interrupts */
> +	reg_write(host, SD_EMMC_STATUS, status);
> +
> +	if (ret == IRQ_HANDLED) {
> +		meson_mmc_read_resp(host->mmc, cmd);
> +		meson_mmc_request_done(host->mmc, cmd->mrq);
> +	}
> +
> +	spin_unlock(&host->lock);
> +	return ret;
> +}
> +
> +static irqreturn_t meson_mmc_irq_thread(int irq, void *dev_id)
> +{
> +	struct meson_host *host = dev_id;
> +	struct mmc_request *mrq = host->mrq;
> +	struct mmc_command *cmd = host->cmd;
> +	struct mmc_data *data;
> +

Drop that newline?

> +	unsigned int xfer_bytes;
> +	int ret = IRQ_HANDLED;
> +
> +	if (WARN_ON(!mrq))
> +		ret = IRQ_NONE;
> +
> +	if (WARN_ON(!cmd))
> +		ret = IRQ_NONE;
> +
> +	data = cmd->data;
> +	if (data) {
> +		xfer_bytes = data->blksz * data->blocks;
> +		if (data->flags & MMC_DATA_READ) {
> +			WARN_ON(xfer_bytes > host->bounce_buf_size);
> +			sg_copy_from_buffer(data->sg, data->sg_len,
> +					    host->bounce_buf, xfer_bytes);
> +			data->bytes_xfered = xfer_bytes;
> +		}
> +	}
> +
> +	meson_mmc_read_resp(host->mmc, cmd);
> +	if (!data || !data->stop || mrq->sbc)
> +		meson_mmc_request_done(host->mmc, mrq);
> +	else
> +		meson_mmc_start_cmd(host->mmc, data->stop);
> +
> +	return ret;
> +}
> +
> +/*
> + * NOTE: we only need this until the GPIO/pinctrl driver can handle
> + * interrupts.  For now, the MMC core will use this for polling.
> + */
> +static int meson_mmc_get_cd(struct mmc_host *mmc)
> +{
> +	int status = mmc_gpio_get_cd(mmc);
> +
> +	if (status == -ENOSYS)
> +		return 1; /* assume present */
> +
> +	return status;
> +}
> +
> +static struct mmc_host_ops meson_mmc_ops = {

const?

> +	.request	= meson_mmc_request,
> +	.set_ios	= meson_mmc_set_ios,
> +	.get_cd         = meson_mmc_get_cd,
> +};
> +
> +static int meson_mmc_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct resource *res;
> +	struct meson_host *host;
> +	struct mmc_host *mmc;
> +	int ret;
> +
> +	mmc = mmc_alloc_host(sizeof(struct meson_host), &pdev->dev);
> +	if (!mmc)
> +		return -ENOMEM;
> +	host = mmc_priv(mmc);
> +	host->mmc = mmc;
> +	host->dev = &pdev->dev;
> +	dev_set_drvdata(&pdev->dev, host);
> +
> +	spin_lock_init(&host->lock);
> +
> +	host->core_clk = devm_clk_get(&pdev->dev, "core");
> +	if (IS_ERR(host->core_clk)) {
> +		ret = PTR_ERR(host->core_clk);
> +		if (ret == -EPROBE_DEFER)
> +			dev_dbg(&pdev->dev,
> +				"Missing core clock.  EPROBE_DEFER\n");
> +		else
> +			dev_err(&pdev->dev,
> +				"Unable to get core clk (ret=%d).\n", ret);
> +		goto free_host;
> +	}
> +
> +	/* Voltage supply */
> +	mmc_of_parse_voltage(np, &host->ocr_mask);
> +	ret = mmc_regulator_get_supply(mmc);
> +	if (ret == -EPROBE_DEFER) {
> +		dev_dbg(&pdev->dev, "Missing regulator: EPROBE_DEFER");
> +		goto free_host;
> +	}
> +
> +	if (!mmc->ocr_avail)
> +		mmc->ocr_avail = host->ocr_mask;
> +
> +	ret = mmc_of_parse(mmc);
> +	if (ret) {
> +		dev_warn(&pdev->dev, "error parsing DT: %d\n", ret);
> +		goto free_host;
> +	}
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		ret = -ENODEV;
> +		goto free_host;
> +	}

This if can be dropped and go right into devm_ioremap_resource().

> +	host->regs = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(host->regs)) {
> +		ret = PTR_ERR(host->regs);
> +		goto free_host;
> +	}
> +
> +	host->irq = platform_get_irq(pdev, 0);
> +	if (host->irq == 0) {
> +		dev_err(&pdev->dev, "failed to get interrupt resource.\n");
> +		ret = -EINVAL;
> +		goto free_host;
> +	}
> +
> +	ret = devm_request_threaded_irq(&pdev->dev, host->irq,
> +					meson_mmc_irq, meson_mmc_irq_thread,
> +					IRQF_SHARED, DRIVER_NAME, host);
> +	if (ret)
> +		goto free_host;
> +
> +	/* data bounce buffer */
> +	host->bounce_buf_size = SZ_512K;
> +	host->bounce_buf =
> +		dma_alloc_coherent(host->dev, host->bounce_buf_size,
> +				   &host->bounce_dma_addr, GFP_KERNEL);
> +	if (host->bounce_buf == NULL) {
> +		dev_err(host->dev, "Unable to map allocate DMA bounce buffer.\n");
> +		ret = -ENOMEM;
> +		goto free_host;
> +	}
> +
> +	clk_prepare_enable(host->core_clk);

This can fail.

> +
> +	ret = meson_mmc_clk_init(host);
> +	if (ret)
> +		goto free_host;
> +
> +	/* Stop execution */
> +	reg_write(host, SD_EMMC_START, 0);
> +
> +	/* clear, ack, enable all interrupts */
> +	reg_write(host, SD_EMMC_IRQ_EN, 0);
> +	reg_write(host, SD_EMMC_STATUS, IRQ_EN_MASK);

Shouldn't we do this before requesting the interrupt?

> +
> +	mmc->ops = &meson_mmc_ops;
> +	mmc_add_host(mmc);
> +
> +	return 0;
> +
> +free_host:
> +	dev_dbg(host->dev, "Failed to probe: ret=%d\n", ret);
> +	if (host->core_clk)
> +		clk_disable_unprepare(host->core_clk);
> +	mmc_free_host(mmc);
> +	return ret;
> +}
> +

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