[PATCH v3 1/3] scsi: ufs: add write booster feature support

From: Asutosh Das
Date: Wed Apr 22 2020 - 17:42:04 EST

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The write performance of TLC NAND is considerably
lower than SLC NAND. Using SLC NAND as a WriteBooster
Buffer enables the write request to be processed with
lower latency and improves the overall write performance.

Adds support for shared-buffer mode WriteBooster.

WriteBooster enable: SW enables it when clocks are
scaled up, thus it's enabled only in high load conditions.

WriteBooster disable: SW will disable the feature,
when clocks are scaled down. Thus writes would go as normal
writes.

To keep the endurance of the WriteBooster Buffer at a
maximum, this load based toggling is adopted.

Signed-off-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
---
drivers/scsi/ufs/ufs.h | 31 +++++-
drivers/scsi/ufs/ufshcd.c | 252 +++++++++++++++++++++++++++++++++++++++++++++-
drivers/scsi/ufs/ufshcd.h | 14 +++
3 files changed, 291 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
index 990cb48..d77512d 100644
--- a/drivers/scsi/ufs/ufs.h
+++ b/drivers/scsi/ufs/ufs.h
@@ -140,6 +140,9 @@ enum flag_idn {
QUERY_FLAG_IDN_BUSY_RTC = 0x09,
QUERY_FLAG_IDN_RESERVED3 = 0x0A,
QUERY_FLAG_IDN_PERMANENTLY_DISABLE_FW_UPDATE = 0x0B,
+ QUERY_FLAG_IDN_WB_EN = 0x0E,
+ QUERY_FLAG_IDN_WB_BUFF_FLUSH_EN = 0x0F,
+ QUERY_FLAG_IDN_WB_BUFF_FLUSH_DURING_HIBERN8 = 0x10,
};

/* Attribute idn for Query requests */
@@ -168,6 +171,10 @@ enum attr_idn {
QUERY_ATTR_IDN_PSA_STATE = 0x15,
QUERY_ATTR_IDN_PSA_DATA_SIZE = 0x16,
QUERY_ATTR_IDN_REF_CLK_GATING_WAIT_TIME = 0x17,
+ QUERY_ATTR_IDN_WB_FLUSH_STATUS = 0x1C,
+ QUERY_ATTR_IDN_AVAIL_WB_BUFF_SIZE = 0x1D,
+ QUERY_ATTR_IDN_WB_BUFF_LIFE_TIME_EST = 0x1E,
+ QUERY_ATTR_IDN_CURR_WB_BUFF_SIZE = 0x1F,
};

/* Descriptor idn for Query requests */
@@ -191,9 +198,9 @@ enum desc_header_offset {
};

enum ufs_desc_def_size {
- QUERY_DESC_DEVICE_DEF_SIZE = 0x40,
+ QUERY_DESC_DEVICE_DEF_SIZE = 0x59,
QUERY_DESC_CONFIGURATION_DEF_SIZE = 0x90,
- QUERY_DESC_UNIT_DEF_SIZE = 0x23,
+ QUERY_DESC_UNIT_DEF_SIZE = 0x2D,
QUERY_DESC_INTERCONNECT_DEF_SIZE = 0x06,
QUERY_DESC_GEOMETRY_DEF_SIZE = 0x48,
QUERY_DESC_POWER_DEF_SIZE = 0x62,
@@ -219,6 +226,7 @@ enum unit_desc_param {
UNIT_DESC_PARAM_PHY_MEM_RSRC_CNT = 0x18,
UNIT_DESC_PARAM_CTX_CAPABILITIES = 0x20,
UNIT_DESC_PARAM_LARGE_UNIT_SIZE_M1 = 0x22,
+ UNIT_DESC_PARAM_WB_BUF_ALLOC_UNITS = 0x29,
};

/* Device descriptor parameters offsets in bytes*/
@@ -258,6 +266,10 @@ enum device_desc_param {
DEVICE_DESC_PARAM_PSA_MAX_DATA = 0x25,
DEVICE_DESC_PARAM_PSA_TMT = 0x29,
DEVICE_DESC_PARAM_PRDCT_REV = 0x2A,
+ DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP = 0x4F,
+ DEVICE_DESC_PARAM_WB_PRESRV_USRSPC_EN = 0x53,
+ DEVICE_DESC_PARAM_WB_TYPE = 0x54,
+ DEVICE_DESC_PARAM_WB_SHARED_ALLOC_UNITS = 0x55,
};

/* Interconnect descriptor parameters offsets in bytes*/
@@ -333,6 +345,11 @@ enum {
UFSHCD_AMP = 3,
};

+/* Possible values for dExtendedUFSFeaturesSupport */
+enum {
+ UFS_DEV_WRITE_BOOSTER_SUP = BIT(8),
+};
+
#define POWER_DESC_MAX_SIZE 0x62
#define POWER_DESC_MAX_ACTV_ICC_LVLS 16

@@ -447,6 +464,11 @@ enum ufs_dev_pwr_mode {
UFS_POWERDOWN_PWR_MODE = 3,
};

+enum ufs_dev_wb_buf_avail_size {
+ UFS_WB_10_PERCENT_BUF_REMAIN = 0x1,
+ UFS_WB_40_PERCENT_BUF_REMAIN = 0x4,
+};
+
/**
* struct utp_cmd_rsp - Response UPIU structure
* @residual_transfer_count: Residual transfer count DW-3
@@ -537,6 +559,11 @@ struct ufs_dev_info {
u8 *model;
u16 wspecversion;
u32 clk_gating_wait_us;
+ u32 d_ext_ufs_feature_sup;
+ u8 b_wb_buffer_type;
+ u32 d_wb_alloc_units;
+ bool keep_vcc_on;
+ u8 b_presrv_uspc_en;
};

/**
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 7d1fa13..b0d6c1e 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -48,6 +48,8 @@
#include "unipro.h"
#include "ufs-sysfs.h"
#include "ufs_bsg.h"
+#include <asm/unaligned.h>
+#include <linux/blkdev.h>

#define CREATE_TRACE_POINTS
#include <trace/events/ufs.h>
@@ -251,6 +253,13 @@ static int ufshcd_scale_clks(struct ufs_hba *hba, bool scale_up);
static irqreturn_t ufshcd_intr(int irq, void *__hba);
static int ufshcd_change_power_mode(struct ufs_hba *hba,
struct ufs_pa_layer_attr *pwr_mode);
+static bool ufshcd_wb_sup(struct ufs_hba *hba);
+static int ufshcd_wb_buf_flush_enable(struct ufs_hba *hba);
+static int ufshcd_wb_buf_flush_disable(struct ufs_hba *hba);
+static int ufshcd_wb_ctrl(struct ufs_hba *hba, bool enable);
+static int ufshcd_wb_toggle_flush_during_h8(struct ufs_hba *hba, bool set);
+static inline void ufshcd_wb_toggle_flush(struct ufs_hba *hba, bool enable);
+
static inline bool ufshcd_valid_tag(struct ufs_hba *hba, int tag)
{
return tag >= 0 && tag < hba->nutrs;
@@ -272,6 +281,25 @@ static inline void ufshcd_disable_irq(struct ufs_hba *hba)
}
}

+static inline void ufshcd_wb_config(struct ufs_hba *hba)
+{
+ int ret;
+
+ if (!ufshcd_wb_sup(hba))
+ return;
+
+ ret = ufshcd_wb_ctrl(hba, true);
+ if (ret)
+ dev_err(hba->dev, "%s: Enable WB failed: %d\n", __func__, ret);
+ else
+ dev_info(hba->dev, "%s: Write Booster Configured\n", __func__);
+ ret = ufshcd_wb_toggle_flush_during_h8(hba, true);
+ if (ret)
+ dev_err(hba->dev, "%s: En WB flush during H8: failed: %d\n",
+ __func__, ret);
+ ufshcd_wb_toggle_flush(hba, true);
+}
+
static void ufshcd_scsi_unblock_requests(struct ufs_hba *hba)
{
if (atomic_dec_and_test(&hba->scsi_block_reqs_cnt))
@@ -1150,10 +1178,17 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
/* scale up the gear after scaling up clocks */
if (scale_up) {
ret = ufshcd_scale_gear(hba, true);
- if (ret)
+ if (ret) {
ufshcd_scale_clks(hba, false);
+ goto out_unprepare;
+ }
}

+ /* Enable Write Booster if we have scaled up else disable it */
+ up_write(&hba->clk_scaling_lock);
+ ufshcd_wb_ctrl(hba, scale_up);
+ down_write(&hba->clk_scaling_lock);
+
out_unprepare:
ufshcd_clock_scaling_unprepare(hba);
out:
@@ -5161,6 +5196,166 @@ static void ufshcd_bkops_exception_event_handler(struct ufs_hba *hba)
__func__, err);
}

+static bool ufshcd_wb_sup(struct ufs_hba *hba)
+{
+ return ufshcd_is_wb_allowed(hba);
+}
+
+static int ufshcd_wb_ctrl(struct ufs_hba *hba, bool enable)
+{
+ int ret;
+ enum query_opcode opcode;
+
+ if (!ufshcd_wb_sup(hba))
+ return 0;
+
+ if (!(enable ^ hba->wb_enabled))
+ return 0;
+ if (enable)
+ opcode = UPIU_QUERY_OPCODE_SET_FLAG;
+ else
+ opcode = UPIU_QUERY_OPCODE_CLEAR_FLAG;
+
+ ret = ufshcd_query_flag_retry(hba, opcode,
+ QUERY_FLAG_IDN_WB_EN, NULL);
+ if (ret) {
+ dev_err(hba->dev, "%s write booster %s failed %d\n",
+ __func__, enable ? "enable" : "disable", ret);
+ return ret;
+ }
+
+ hba->wb_enabled = enable;
+ dev_dbg(hba->dev, "%s write booster %s %d\n",
+ __func__, enable ? "enable" : "disable", ret);
+
+ return ret;
+}
+
+static int ufshcd_wb_toggle_flush_during_h8(struct ufs_hba *hba, bool set)
+{
+ int val;
+
+ if (set)
+ val = UPIU_QUERY_OPCODE_SET_FLAG;
+ else
+ val = UPIU_QUERY_OPCODE_CLEAR_FLAG;
+
+ return ufshcd_query_flag_retry(hba, val,
+ QUERY_FLAG_IDN_WB_BUFF_FLUSH_DURING_HIBERN8,
+ NULL);
+}
+
+static inline void ufshcd_wb_toggle_flush(struct ufs_hba *hba, bool enable)
+{
+ if (enable)
+ ufshcd_wb_buf_flush_enable(hba);
+ else
+ ufshcd_wb_buf_flush_disable(hba);
+
+}
+
+static int ufshcd_wb_buf_flush_enable(struct ufs_hba *hba)
+{
+ int ret;
+
+ if (!ufshcd_wb_sup(hba) || hba->wb_buf_flush_enabled)
+ return 0;
+
+ ret = ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_SET_FLAG,
+ QUERY_FLAG_IDN_WB_BUFF_FLUSH_EN, NULL);
+ if (ret)
+ dev_err(hba->dev, "%s WB - buf flush enable failed %d\n",
+ __func__, ret);
+ else
+ hba->wb_buf_flush_enabled = true;
+
+ dev_dbg(hba->dev, "WB - Flush enabled: %d\n", ret);
+ return ret;
+}
+
+static int ufshcd_wb_buf_flush_disable(struct ufs_hba *hba)
+{
+ int ret;
+
+ if (!ufshcd_wb_sup(hba) || !hba->wb_buf_flush_enabled)
+ return 0;
+
+ ret = ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_CLEAR_FLAG,
+ QUERY_FLAG_IDN_WB_BUFF_FLUSH_EN, NULL);
+ if (ret) {
+ dev_warn(hba->dev, "%s: WB - buf flush disable failed %d\n",
+ __func__, ret);
+ } else {
+ hba->wb_buf_flush_enabled = false;
+ dev_dbg(hba->dev, "WB - Flush disabled: %d\n", ret);
+ }
+
+ return ret;
+}
+
+static bool ufshcd_wb_presrv_usrspc_keep_vcc_on(struct ufs_hba *hba,
+ u32 avail_buf)
+{
+ u32 cur_buf;
+ int ret;
+
+ ret = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
+ QUERY_ATTR_IDN_CURR_WB_BUFF_SIZE,
+ 0, 0, &cur_buf);
+ if (ret) {
+ dev_err(hba->dev, "%s dCurWriteBoosterBufferSize read failed %d\n",
+ __func__, ret);
+ return false;
+ }
+
+ if (!cur_buf) {
+ dev_info(hba->dev, "dCurWBBuf: %d WB disabled until free-space is available\n",
+ cur_buf);
+ return false;
+ }
+ /* Let it continue to flush when >60% full */
+ if (avail_buf < UFS_WB_40_PERCENT_BUF_REMAIN)
+ return true;
+
+ return false;
+}
+
+static bool ufshcd_wb_keep_vcc_on(struct ufs_hba *hba)
+{
+ int ret;
+ u32 avail_buf;
+
+ if (!ufshcd_wb_sup(hba))
+ return false;
+ /*
+ * The ufs device needs the vcc to be ON to flush.
+ * With user-space reduction enabled, it's enough to enable flush
+ * by checking only the available buffer. The threshold
+ * defined here is > 90% full.
+ * With user-space preserved enabled, the current-buffer
+ * should be checked too because the wb buffer size can reduce
+ * when disk tends to be full. This info is provided by current
+ * buffer (dCurrentWriteBoosterBufferSize). There's no point in
+ * keeping vcc on when current buffer is empty.
+ */
+ ret = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
+ QUERY_ATTR_IDN_AVAIL_WB_BUFF_SIZE,
+ 0, 0, &avail_buf);
+ if (ret) {
+ dev_warn(hba->dev, "%s dAvailableWriteBoosterBufferSize read failed %d\n",
+ __func__, ret);
+ return false;
+ }
+
+ if (!hba->dev_info.b_presrv_uspc_en) {
+ if (avail_buf <= UFS_WB_10_PERCENT_BUF_REMAIN)
+ return true;
+ return false;
+ }
+
+ return ufshcd_wb_presrv_usrspc_keep_vcc_on(hba, avail_buf);
+}
+
/**
* ufshcd_exception_event_handler - handle exceptions raised by device
* @work: pointer to work data
@@ -6603,6 +6798,33 @@ static int ufshcd_scsi_add_wlus(struct ufs_hba *hba)
return ret;
}

+static void ufshcd_wb_probe(struct ufs_hba *hba, u8 *desc_buf)
+{
+ hba->dev_info.d_ext_ufs_feature_sup =
+ get_unaligned_be32(desc_buf +
+ DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP);
+ /*
+ * WB may be supported but not configured while provisioning.
+ * The spec says, in dedicated wb buffer mode,
+ * a max of 1 lun would have wb buffer configured.
+ * Now only shared buffer mode is supported.
+ */
+ hba->dev_info.b_wb_buffer_type =
+ desc_buf[DEVICE_DESC_PARAM_WB_TYPE];
+
+ hba->dev_info.d_wb_alloc_units =
+ get_unaligned_be32(desc_buf +
+ DEVICE_DESC_PARAM_WB_SHARED_ALLOC_UNITS);
+ hba->dev_info.b_presrv_uspc_en =
+ desc_buf[DEVICE_DESC_PARAM_WB_PRESRV_USRSPC_EN];
+
+ if (!((hba->dev_info.d_ext_ufs_feature_sup &
+ UFS_DEV_WRITE_BOOSTER_SUP) &&
+ hba->dev_info.b_wb_buffer_type &&
+ hba->dev_info.d_wb_alloc_units))
+ hba->caps &= ~UFSHCD_CAP_WB_EN;
+}
+
static int ufs_get_device_desc(struct ufs_hba *hba)
{
int err;
@@ -6639,6 +6861,11 @@ static int ufs_get_device_desc(struct ufs_hba *hba)
desc_buf[DEVICE_DESC_PARAM_SPEC_VER + 1];

model_index = desc_buf[DEVICE_DESC_PARAM_PRDCT_NAME];
+
+ /* Enable WB only for UFS-3.1 */
+ if (dev_info->wspecversion >= 0x310)
+ ufshcd_wb_probe(hba, desc_buf);
+
err = ufshcd_read_string_desc(hba, model_index,
&dev_info->model, SD_ASCII_STD);
if (err < 0) {
@@ -7149,6 +7376,7 @@ static int ufshcd_probe_hba(struct ufs_hba *hba, bool async)
/* set the state as operational after switching to desired gear */
hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;

+ ufshcd_wb_config(hba);
/* Enable Auto-Hibernate if configured */
ufshcd_auto_hibern8_enable(hba);

@@ -7809,12 +8037,16 @@ static void ufshcd_vreg_set_lpm(struct ufs_hba *hba)
*
* Ignore the error returned by ufshcd_toggle_vreg() as device is anyway
* in low power state which would save some power.
+ *
+ * If Write Booster is enabled and the device needs to flush the WB
+ * buffer OR if bkops status is urgent for WB, keep Vcc on.
*/
if (ufshcd_is_ufs_dev_poweroff(hba) && ufshcd_is_link_off(hba) &&
!hba->dev_info.is_lu_power_on_wp) {
ufshcd_setup_vreg(hba, false);
} else if (!ufshcd_is_ufs_dev_active(hba)) {
- ufshcd_toggle_vreg(hba->dev, hba->vreg_info.vcc, false);
+ if (!hba->dev_info.keep_vcc_on)
+ ufshcd_toggle_vreg(hba->dev, hba->vreg_info.vcc, false);
if (!ufshcd_is_link_active(hba)) {
ufshcd_config_vreg_lpm(hba, hba->vreg_info.vccq);
ufshcd_config_vreg_lpm(hba, hba->vreg_info.vccq2);
@@ -7938,11 +8170,23 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
/* make sure that auto bkops is disabled */
ufshcd_disable_auto_bkops(hba);
}
+ /*
+ * With wb enabled, if the bkops is enabled or if the
+ * configured WB type is 70% full, keep vcc ON
+ * for the device to flush the wb buffer
+ */
+ if ((hba->auto_bkops_enabled && ufshcd_wb_sup(hba)) ||
+ ufshcd_wb_keep_vcc_on(hba))
+ hba->dev_info.keep_vcc_on = true;
+ else
+ hba->dev_info.keep_vcc_on = false;
+ } else if (!ufshcd_is_runtime_pm(pm_op)) {
+ hba->dev_info.keep_vcc_on = false;
}

if ((req_dev_pwr_mode != hba->curr_dev_pwr_mode) &&
- ((ufshcd_is_runtime_pm(pm_op) && !hba->auto_bkops_enabled) ||
- !ufshcd_is_runtime_pm(pm_op))) {
+ ((ufshcd_is_runtime_pm(pm_op) && !hba->auto_bkops_enabled) ||
+ !ufshcd_is_runtime_pm(pm_op))) {
/* ensure that bkops is disabled */
ufshcd_disable_auto_bkops(hba);
ret = ufshcd_set_dev_pwr_mode(hba, req_dev_pwr_mode);
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 6ffc08a..056537e 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -555,6 +555,13 @@ enum ufshcd_caps {
* for userspace to control the power management.
*/
UFSHCD_CAP_RPM_AUTOSUSPEND = 1 << 6,
+
+ /*
+ * This capability allows the host controller driver to turn-on
+ * WriteBooster, if the underlying device supports it and is
+ * provisioned to be used. This would increase the write performance.
+ */
+ UFSHCD_CAP_WB_EN = 1 << 7,
};

/**
@@ -727,6 +734,8 @@ struct ufs_hba {

struct device bsg_dev;
struct request_queue *bsg_queue;
+ bool wb_buf_flush_enabled;
+ bool wb_enabled;
};

/* Returns true if clocks can be gated. Otherwise false */
@@ -775,6 +784,11 @@ static inline bool ufshcd_is_auto_hibern8_enabled(struct ufs_hba *hba)
return FIELD_GET(UFSHCI_AHIBERN8_TIMER_MASK, hba->ahit) ? true : false;
}

+static inline bool ufshcd_is_wb_allowed(struct ufs_hba *hba)
+{
+ return hba->caps & UFSHCD_CAP_WB_EN;
+}
+
#define ufshcd_writel(hba, val, reg) \
writel((val), (hba)->mmio_base + (reg))
#define ufshcd_readl(hba, reg) \
--
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