mmc: Test bus-width for old MMC devices

Some old MMC devices fail with the 4/8 bits the driver tries to use
exclusively.  This patch adds a test for the given bus setup and falls
back to the lower bit mode (until 1-bit mode) when the test fails.

[Major rework and refactoring by tiwai]
[Quirk addition and many fixes by prakity]

Signed-off-by: Aries Lee <arieslee@jmicron.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Philip Rakity <prakity@marvell.com>
Tested-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 101 insertions, 0 deletions

diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index 326447c9ede8..60842f878ded 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -462,3 +462,104 @@ int mmc_send_status(struct mmc_card *card, u32 *status)
 	return 0;
 }
 
+static int
+mmc_send_bus_test(struct mmc_card *card, struct mmc_host *host, u8 opcode,
+		  u8 len)
+{
+	struct mmc_request mrq;
+	struct mmc_command cmd;
+	struct mmc_data data;
+	struct scatterlist sg;
+	u8 *data_buf;
+	u8 *test_buf;
+	int i, err;
+	static u8 testdata_8bit[8] = { 0x55, 0xaa, 0, 0, 0, 0, 0, 0 };
+	static u8 testdata_4bit[4] = { 0x5a, 0, 0, 0 };
+
+	/* dma onto stack is unsafe/nonportable, but callers to this
+	 * routine normally provide temporary on-stack buffers ...
+	 */
+	data_buf = kmalloc(len, GFP_KERNEL);
+	if (!data_buf)
+		return -ENOMEM;
+
+	if (len == 8)
+		test_buf = testdata_8bit;
+	else if (len == 4)
+		test_buf = testdata_4bit;
+	else {
+		printk(KERN_ERR "%s: Invalid bus_width %d\n",
+		       mmc_hostname(host), len);
+		kfree(data_buf);
+		return -EINVAL;
+	}
+
+	if (opcode == MMC_BUS_TEST_W)
+		memcpy(data_buf, test_buf, len);
+
+	memset(&mrq, 0, sizeof(struct mmc_request));
+	memset(&cmd, 0, sizeof(struct mmc_command));
+	memset(&data, 0, sizeof(struct mmc_data));
+
+	mrq.cmd = &cmd;
+	mrq.data = &data;
+	cmd.opcode = opcode;
+	cmd.arg = 0;
+
+	/* NOTE HACK:  the MMC_RSP_SPI_R1 is always correct here, but we
+	 * rely on callers to never use this with "native" calls for reading
+	 * CSD or CID.  Native versions of those commands use the R2 type,
+	 * not R1 plus a data block.
+	 */
+	cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
+
+	data.blksz = len;
+	data.blocks = 1;
+	if (opcode == MMC_BUS_TEST_R)
+		data.flags = MMC_DATA_READ;
+	else
+		data.flags = MMC_DATA_WRITE;
+
+	data.sg = &sg;
+	data.sg_len = 1;
+	sg_init_one(&sg, data_buf, len);
+	mmc_wait_for_req(host, &mrq);
+	err = 0;
+	if (opcode == MMC_BUS_TEST_R) {
+		for (i = 0; i < len / 4; i++)
+			if ((test_buf[i] ^ data_buf[i]) != 0xff) {
+				err = -EIO;
+				break;
+			}
+	}
+	kfree(data_buf);
+
+	if (cmd.error)
+		return cmd.error;
+	if (data.error)
+		return data.error;
+
+	return err;
+}
+
+int mmc_bus_test(struct mmc_card *card, u8 bus_width)
+{
+	int err, width;
+
+	if (bus_width == MMC_BUS_WIDTH_8)
+		width = 8;
+	else if (bus_width == MMC_BUS_WIDTH_4)
+		width = 4;
+	else if (bus_width == MMC_BUS_WIDTH_1)
+		return 0; /* no need for test */
+	else
+		return -EINVAL;
+
+	/*
+	 * Ignore errors from BUS_TEST_W.  BUS_TEST_R will fail if there
+	 * is a problem.  This improves chances that the test will work.
+	 */
+	mmc_send_bus_test(card, card->host, MMC_BUS_TEST_W, width);
+	err = mmc_send_bus_test(card, card->host, MMC_BUS_TEST_R, width);
+	return err;
+}