[PATCH 2/2] mmc: sdhci: Add support for O2 hardware tuning

[ernest.zhang]

O2 sd host controllers have a hardware tuning function. In software
tuning mode CPU should send multiple command to host controller but in
hardware tuning mode, CPU need send only one tuning command to sd host
controller. It can improve the speed linux boot from eMMC.

Signed-off-by: ernest.zhang <ernest.zhang@xxxxxxxxxxxxxx>
---
 drivers/mmc/host/sdhci-pci-o2micro.c | 193 +++++++++++++++++++++++++++++++++++
 drivers/mmc/host/sdhci.c             |   5 +-
 2 files changed, 197 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-pci-o2micro.c b/drivers/mmc/host/sdhci-pci-o2micro.c
index 8855a416ffd4..5978ead34827 100644
--- a/drivers/mmc/host/sdhci-pci-o2micro.c
+++ b/drivers/mmc/host/sdhci-pci-o2micro.c
@@ -17,6 +17,12 @@
  */
 
 #include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/fixed.h>
+#include <linux/regulator/machine.h>
+#include <linux/mmc/host.h>
+#include <linux/mmc/mmc.h>
+#include <linux/delay.h>
 
 #include "sdhci.h"
 #include "sdhci-pci.h"
@@ -57,6 +63,192 @@
 #define O2_SD_VENDOR_SETTING2	0x1C8
 #define O2_SD_HW_TUNING_ENABLE	BIT(4)
 
+static void sdhci_o2_start_tuning(struct sdhci_host *host)
+{
+	u16 ctrl;
+
+	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+	ctrl |= SDHCI_CTRL_EXEC_TUNING;
+	sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+
+	/*
+	 * As per the Host Controller spec v3.00, tuning command
+	 * generates Buffer Read Ready interrupt, so enable that.
+	 *
+	 * Note: The spec clearly says that when tuning sequence
+	 * is being performed, the controller does not generate
+	 * interrupts other than Buffer Read Ready interrupt. But
+	 * to make sure we don't hit a controller bug, we _only_
+	 * enable Buffer Read Ready interrupt here.
+	 */
+	sdhci_writel(host, SDHCI_INT_DATA_AVAIL, SDHCI_INT_ENABLE);
+	sdhci_writel(host, SDHCI_INT_DATA_AVAIL, SDHCI_SIGNAL_ENABLE);
+}
+
+static void sdhci_o2_end_tuning(struct sdhci_host *host)
+{
+	sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
+	sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
+}
+
+static inline bool sdhci_data_line_cmd(struct mmc_command *cmd)
+{
+	return cmd->data || cmd->flags & MMC_RSP_BUSY;
+}
+
+static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)
+{
+	if (sdhci_data_line_cmd(mrq->cmd))
+		del_timer(&host->data_timer);
+	else
+		del_timer(&host->timer);
+}
+
+static void sdhci_o2_set_tuning_mode(struct sdhci_host *host)
+{
+	u16 reg;
+
+	/* enable hardware tuning */
+	reg = sdhci_readw(host, O2_SD_VENDOR_SETTING);
+	reg &= ~O2_SD_HW_TUNING_ENABLE;
+	sdhci_writew(host, reg, O2_SD_VENDOR_SETTING);
+}
+
+
+static int sdhci_o2_send_tuning(struct sdhci_host *host, u32 opcode)
+{
+	struct mmc_command cmd = { };
+	struct mmc_data data = { };
+	struct scatterlist sg;
+	struct mmc_request mrq = { };
+	unsigned long flags;
+	u32 b = host->sdma_boundary;
+	int size = 64;
+	u8 *data_buf = kzalloc(size, GFP_KERNEL);
+
+	if (!data_buf)
+		return -ENOMEM;
+
+	cmd.opcode = opcode;
+	cmd.flags = MMC_RSP_PRESENT | MMC_RSP_OPCODE | MMC_RSP_CRC;
+	cmd.mrq = &mrq;
+	cmd.data = NULL;
+	mrq.cmd = &cmd;
+	mrq.data = &data;
+	data.blksz = size;
+	data.blocks = 1;
+	data.flags = MMC_DATA_READ;
+
+	data.timeout_ns = 50 * NSEC_PER_MSEC;
+
+	data.sg = &sg;
+	data.sg_len = 1;
+	sg_init_one(&sg, data_buf, size);
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	sdhci_writew(host, SDHCI_MAKE_BLKSZ(b, 64), SDHCI_BLOCK_SIZE);
+
+	/*
+	 * The tuning block is sent by the card to the host controller.
+	 * So we set the TRNS_READ bit in the Transfer Mode register.
+	 * This also takes care of setting DMA Enable and Multi Block
+	 * Select in the same register to 0.
+	 */
+	sdhci_send_command(host, &cmd);
+
+	host->cmd = NULL;
+
+	sdhci_del_timer(host, &mrq);
+
+	host->tuning_done = 0;
+
+	mmiowb();
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	/* Wait for Buffer Read Ready interrupt */
+	wait_event_timeout(host->buf_ready_int, (host->tuning_done == 1),
+			   msecs_to_jiffies(50));
+	kfree(data_buf);
+	return 0;
+}
+
+static void sdhci_o2_reset_tuning(struct sdhci_host *host)
+{
+	u16 ctrl;
+
+	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+	ctrl &= ~SDHCI_CTRL_TUNED_CLK;
+	ctrl &= ~SDHCI_CTRL_EXEC_TUNING;
+	sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+}
+
+static void __sdhci_o2_execute_tuning(struct sdhci_host *host, u32 opcode)
+{
+	int i;
+
+	sdhci_o2_send_tuning(host, MMC_SEND_TUNING_BLOCK_HS200);
+
+	for (i = 0; i < 150; i++) {
+		u16 ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+
+		if (!(ctrl & SDHCI_CTRL_EXEC_TUNING)) {
+			if (ctrl & SDHCI_CTRL_TUNED_CLK) {
+				host->tuning_done = true;
+				return;
+			}
+			pr_warn("%s: HW tuning failed !\n",
+				   mmc_hostname(host->mmc));
+			break;
+		}
+
+		mdelay(1);
+	}
+
+	pr_info("%s: Tuning failed, falling back to fixed sampling clock\n",
+		mmc_hostname(host->mmc));
+	sdhci_o2_reset_tuning(host);
+}
+
+static int sdhci_o2_execute_tuning(struct mmc_host *mmc, u32 opcode)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	int current_bus_width = 0;
+
+	/*
+	 * This handler only implements the eMMC tuning that is specific to
+	 * this controller.  Fall back to the standard method for other TIMING.
+	 */
+	if (host->timing != MMC_TIMING_MMC_HS200)
+		return sdhci_execute_tuning(mmc, opcode);
+
+	if (WARN_ON(opcode != MMC_SEND_TUNING_BLOCK_HS200))
+		return -EINVAL;
+
+	/*
+	 * o2 sdhci host didn't support 8bit emmc tuning
+	 */
+	if (mmc->ios.bus_width == MMC_BUS_WIDTH_8) {
+		current_bus_width = mmc->ios.bus_width;
+		sdhci_set_bus_width(host, MMC_BUS_WIDTH_4);
+	}
+
+	sdhci_o2_set_tuning_mode(host);
+
+	sdhci_o2_start_tuning(host);
+
+	__sdhci_o2_execute_tuning(host, opcode);
+
+	sdhci_o2_end_tuning(host);
+
+	if (current_bus_width == MMC_BUS_WIDTH_8) {
+		sdhci_set_bus_width(host, current_bus_width);
+	}
+
+	host->flags &= ~SDHCI_HS400_TUNING;
+	return 0;
+}
+
 static void o2_pci_set_baseclk(struct sdhci_pci_chip *chip, u32 value)
 {
 	u32 scratch_32;
@@ -214,6 +406,7 @@ int sdhci_pci_o2_probe_slot(struct sdhci_pci_slot *slot)
 			}
 		}
 
+		host->mmc_host_ops.execute_tuning = sdhci_o2_execute_tuning;
 
 		if (chip->pdev->device != PCI_DEVICE_ID_O2_FUJIN2)
 			break;
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index e9290a3439d5..8ed7afc84f7a 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -919,7 +919,10 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host,
 	if (data == NULL) {
 		if (host->quirks2 &
 			SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD) {
-			sdhci_writew(host, 0x0, SDHCI_TRANSFER_MODE);
+			/* must not clear SDHCI_TRANSFER_MODE when tuning */
+			if (cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200) {
+				sdhci_writew(host, 0x0, SDHCI_TRANSFER_MODE);
+			}
 		} else {
 		/* clear Auto CMD settings for no data CMDs */
 			mode = sdhci_readw(host, SDHCI_TRANSFER_MODE);
-- 
2.14.1