[PATCH net-next 0/4] net: ipa: IPA v4.5 aggregation and Qtime

[PATCH net-next 0/4] net: ipa: IPA v4.5 aggregation and Qtime

[Alex Elder]

This series updates some IPA register definitions that change in
substantive ways for IPA v4.5.

One register defines parameters used by an endpoint to aggregate
multiple packets into a buffer.  The size and position of most
fields in that register have changed with this new hardware version,
and consequently the function that programs it needs to be done a
bit differently.  The first patch takes care of this.

Second, IPA v4.5 introduces a unified time keeping component to be
used in several places by the IPA hardware.  A main clock divider
provides a fundamental tick rate, and several timestamped features 
now define their granularity based on that.  There is also a set of
"pulse generators" derived from the main tick, and these are used
to implement timers used for aggregation and head-of-line block
avoidance.  The second patch adds IPA register updates to support
Qtime along with its configuration, and the last two patches
configure the timers that use it.

					-Alex

Alex Elder (4):
  net: ipa: update IPA aggregation registers for IPA v4.5
  net: ipa: set up IPA v4.5 Qtime configuration
  net: ipa: use Qtime for IPA v4.5 aggregation time limit
  net: ipa: use Qtime for IPA v4.5 head-of-line time limit

 drivers/net/ipa/ipa_endpoint.c | 174 +++++++++++++++++++++++++--------
 drivers/net/ipa/ipa_main.c     |  67 ++++++++++++-
 drivers/net/ipa/ipa_reg.h      |  68 +++++++++++--
 3 files changed, 260 insertions(+), 49 deletions(-)

-- 
2.20.1

[PATCH net-next 1/4] net: ipa: update IPA aggregation registers for IPA v4.5

[Alex Elder]

IPA v4.5 significantly changes the format of the configuration
register used for endpoint aggregation.  The AGGR_BYTE_LIMIT field
is now larger, and the positions of other fields are shifted.  This
complicates the way we have to access this register because functions
like u32_encode_bits() require their field mask argument to be constant.

A further complication is that we want to know the maximum value
representable by at least one of these fields, and that too requires
a constant field mask.

This patch adds support for IPA v4.5 endpoint aggregation registers
in a way that continues to support "legacy" IPA hardware.  It does
so in a way that keeps field masks constant.

First, for each variable field mask, we define an inline function
whose return value is either the legacy value or the IPA v4.5 value.

Second, we define functions for these fields that encode a value
to use in each field based on the IPA version (this approach is
already used elsewhere).  The field mask provided is supplied by
the function mentioned above.

Finally, for the aggregation byte limit fields where we want to
know the maximum representable value, we define a function that
returns that maximum, computed from the appropriate field mask.

We can no longer verify at build time that our buffer size is
in the range that can be represented by the aggregation byte
limit field.  So remove the test done by a BUILD_BUG_ON() call
in ipa_endpoint_validate_build(), and implement a comparable check
at the top of ipa_endpoint_data_valid().

Doing that makes ipa_endpoint_validate_build() contain a single
line BUILD_BUG_ON() call, so just remove that function and move
the remaining line into ipa_endpoint_data_valid().

One final note:  the aggregation time limit value for IPA v4.5 needs
to be computed differently.  That is handled in an upcoming patch.

Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ipa/ipa_endpoint.c | 102 ++++++++++++++++++++++-----------
 drivers/net/ipa/ipa_reg.h      |  38 ++++++++++--
 2 files changed, 101 insertions(+), 39 deletions(-)

diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
index 27f543b6780b1..f260c80f50649 100644
--- a/drivers/net/ipa/ipa_endpoint.c
+++ b/drivers/net/ipa/ipa_endpoint.c
@@ -37,7 +37,7 @@
 #define IPA_ENDPOINT_QMAP_METADATA_MASK		0x000000ff /* host byte order */
 
 #define IPA_ENDPOINT_RESET_AGGR_RETRY_MAX	3
-#define IPA_AGGR_TIME_LIMIT_DEFAULT		500	/* microseconds */
+#define IPA_AGGR_TIME_LIMIT			500	/* microseconds */
 
 /** enum ipa_status_opcode - status element opcode hardware values */
 enum ipa_status_opcode {
@@ -74,31 +74,6 @@ struct ipa_status {
 
 #ifdef IPA_VALIDATE
 
-static void ipa_endpoint_validate_build(void)
-{
-	/* The aggregation byte limit defines the point at which an
-	 * aggregation window will close.  It is programmed into the
-	 * IPA hardware as a number of KB.  We don't use "hard byte
-	 * limit" aggregation, which means that we need to supply
-	 * enough space in a receive buffer to hold a complete MTU
-	 * plus normal skb overhead *after* that aggregation byte
-	 * limit has been crossed.
-	 *
-	 * This check just ensures we don't define a receive buffer
-	 * size that would exceed what we can represent in the field
-	 * that is used to program its size.
-	 */
-	BUILD_BUG_ON(IPA_RX_BUFFER_SIZE >
-		     field_max(AGGR_BYTE_LIMIT_FMASK) * SZ_1K +
-		     IPA_MTU + IPA_RX_BUFFER_OVERHEAD);
-
-	/* I honestly don't know where this requirement comes from.  But
-	 * it holds, and if we someday need to loosen the constraint we
-	 * can try to track it down.
-	 */
-	BUILD_BUG_ON(sizeof(struct ipa_status) % 4);
-}
-
 static bool ipa_endpoint_data_valid_one(struct ipa *ipa, u32 count,
 			    const struct ipa_gsi_endpoint_data *all_data,
 			    const struct ipa_gsi_endpoint_data *data)
@@ -180,14 +155,24 @@ static bool ipa_endpoint_data_valid_one(struct ipa *ipa, u32 count,
 	return true;
 }
 
+static u32 aggr_byte_limit_max(enum ipa_version version)
+{
+	if (version < IPA_VERSION_4_5)
+		return field_max(aggr_byte_limit_fmask(true));
+
+	return field_max(aggr_byte_limit_fmask(false));
+}
+
 static bool ipa_endpoint_data_valid(struct ipa *ipa, u32 count,
 				    const struct ipa_gsi_endpoint_data *data)
 {
 	const struct ipa_gsi_endpoint_data *dp = data;
 	struct device *dev = &ipa->pdev->dev;
 	enum ipa_endpoint_name name;
+	u32 limit;
 
-	ipa_endpoint_validate_build();
+	/* Not sure where this constraint come from... */
+	BUILD_BUG_ON(sizeof(struct ipa_status) % 4);
 
 	if (count > IPA_ENDPOINT_COUNT) {
 		dev_err(dev, "too many endpoints specified (%u > %u)\n",
@@ -195,6 +180,26 @@ static bool ipa_endpoint_data_valid(struct ipa *ipa, u32 count,
 		return false;
 	}
 
+	/* The aggregation byte limit defines the point at which an
+	 * aggregation window will close.  It is programmed into the
+	 * IPA hardware as a number of KB.  We don't use "hard byte
+	 * limit" aggregation, which means that we need to supply
+	 * enough space in a receive buffer to hold a complete MTU
+	 * plus normal skb overhead *after* that aggregation byte
+	 * limit has been crossed.
+	 *
+	 * This check ensures we don't define a receive buffer size
+	 * that would exceed what we can represent in the field that
+	 * is used to program its size.
+	 */
+	limit = aggr_byte_limit_max(ipa->version) * SZ_1K;
+	limit += IPA_MTU + IPA_RX_BUFFER_OVERHEAD;
+	if (limit < IPA_RX_BUFFER_SIZE) {
+		dev_err(dev, "buffer size too big for aggregation (%u > %u)\n",
+			IPA_RX_BUFFER_SIZE, limit);
+		return false;
+	}
+
 	/* Make sure needed endpoints have defined data */
 	if (ipa_gsi_endpoint_data_empty(&data[IPA_ENDPOINT_AP_COMMAND_TX])) {
 		dev_err(dev, "command TX endpoint not defined\n");
@@ -624,29 +629,60 @@ static u32 ipa_aggr_size_kb(u32 rx_buffer_size)
 	return rx_buffer_size / SZ_1K;
 }
 
+/* Encoded values for AGGR endpoint register fields */
+static u32 aggr_byte_limit_encoded(enum ipa_version version, u32 limit)
+{
+	if (version < IPA_VERSION_4_5)
+		return u32_encode_bits(limit, aggr_byte_limit_fmask(true));
+
+	return u32_encode_bits(limit, aggr_byte_limit_fmask(false));
+}
+
+static u32 aggr_time_limit_encoded(enum ipa_version version, u32 limit)
+{
+	/* Convert limit (microseconds) to aggregation timer ticks */
+	limit = DIV_ROUND_CLOSEST(limit, IPA_AGGR_GRANULARITY);
+	if (version < IPA_VERSION_4_5)
+		return u32_encode_bits(limit, aggr_time_limit_fmask(true));
+
+	return u32_encode_bits(limit, aggr_time_limit_fmask(false));
+}
+
+static u32 aggr_sw_eof_active_encoded(enum ipa_version version, bool enabled)
+{
+	u32 val = enabled ? 1 : 0;
+
+	if (version < IPA_VERSION_4_5)
+		return u32_encode_bits(val, aggr_sw_eof_active_fmask(true));
+
+	return u32_encode_bits(val, aggr_sw_eof_active_fmask(false));
+}
+
 static void ipa_endpoint_init_aggr(struct ipa_endpoint *endpoint)
 {
 	u32 offset = IPA_REG_ENDP_INIT_AGGR_N_OFFSET(endpoint->endpoint_id);
+	enum ipa_version version = endpoint->ipa->version;
 	u32 val = 0;
 
 	if (endpoint->data->aggregation) {
 		if (!endpoint->toward_ipa) {
+			bool close_eof;
 			u32 limit;
 
 			val |= u32_encode_bits(IPA_ENABLE_AGGR, AGGR_EN_FMASK);
 			val |= u32_encode_bits(IPA_GENERIC, AGGR_TYPE_FMASK);
 
 			limit = ipa_aggr_size_kb(IPA_RX_BUFFER_SIZE);
-			val |= u32_encode_bits(limit, AGGR_BYTE_LIMIT_FMASK);
+			val |= aggr_byte_limit_encoded(version, limit);
 
-			limit = IPA_AGGR_TIME_LIMIT_DEFAULT;
-			limit = DIV_ROUND_CLOSEST(limit, IPA_AGGR_GRANULARITY);
-			val |= u32_encode_bits(limit, AGGR_TIME_LIMIT_FMASK);
+			limit = IPA_AGGR_TIME_LIMIT;
+			val |= aggr_time_limit_encoded(version, limit);
 
 			/* AGGR_PKT_LIMIT is 0 (unlimited) */
 
-			if (endpoint->data->rx.aggr_close_eof)
-				val |= AGGR_SW_EOF_ACTIVE_FMASK;
+			close_eof = endpoint->data->rx.aggr_close_eof;
+			val |= aggr_sw_eof_active_encoded(version, close_eof);
+
 			/* AGGR_HARD_BYTE_LIMIT_ENABLE is 0 */
 		} else {
 			val |= u32_encode_bits(IPA_ENABLE_DEAGGR,
diff --git a/drivers/net/ipa/ipa_reg.h b/drivers/net/ipa/ipa_reg.h
index 3fabafd7e32c6..09dcfa2998f04 100644
--- a/drivers/net/ipa/ipa_reg.h
+++ b/drivers/net/ipa/ipa_reg.h
@@ -450,12 +450,38 @@ enum ipa_mode {
 					(0x00000824 +  0x0070 * (ep))
 #define AGGR_EN_FMASK				GENMASK(1, 0)
 #define AGGR_TYPE_FMASK				GENMASK(4, 2)
-#define AGGR_BYTE_LIMIT_FMASK			GENMASK(9, 5)
-#define AGGR_TIME_LIMIT_FMASK			GENMASK(14, 10)
-#define AGGR_PKT_LIMIT_FMASK			GENMASK(20, 15)
-#define AGGR_SW_EOF_ACTIVE_FMASK		GENMASK(21, 21)
-#define AGGR_FORCE_CLOSE_FMASK			GENMASK(22, 22)
-#define AGGR_HARD_BYTE_LIMIT_ENABLE_FMASK	GENMASK(24, 24)
+static inline u32 aggr_byte_limit_fmask(bool legacy)
+{
+	return legacy ? GENMASK(9, 5) : GENMASK(10, 5);
+}
+
+static inline u32 aggr_time_limit_fmask(bool legacy)
+{
+	return legacy ? GENMASK(14, 10) : GENMASK(16, 12);
+}
+
+static inline u32 aggr_pkt_limit_fmask(bool legacy)
+{
+	return legacy ? GENMASK(20, 15) : GENMASK(22, 17);
+}
+
+static inline u32 aggr_sw_eof_active_fmask(bool legacy)
+{
+	return legacy ? GENMASK(21, 21) : GENMASK(23, 23);
+}
+
+static inline u32 aggr_force_close_fmask(bool legacy)
+{
+	return legacy ? GENMASK(22, 22) : GENMASK(24, 24);
+}
+
+static inline u32 aggr_hard_byte_limit_enable_fmask(bool legacy)
+{
+	return legacy ? GENMASK(24, 24) : GENMASK(26, 26);
+}
+
+/* The next field is present for IPA v4.5 */
+#define AGGR_GRAN_SEL_FMASK			GENMASK(27, 27)
 
 /** enum ipa_aggr_en - aggregation enable field in ENDP_INIT_AGGR_N */
 enum ipa_aggr_en {
-- 
2.20.1

[PATCH net-next 2/4] net: ipa: set up IPA v4.5 Qtime configuration

[Alex Elder]

IPA v4.5 introduces a new unified timer architecture driven on the
19.2 MHz SoC crystal oscillator (XO).  It is independent of the IPA
core clock and avoids some duplication.

Lower-resolution time stamps are derived from this by using only the
high-order bits of the 19.2 MHz Qtime clock.  And timers are derived
from this based on "pulse generators" configured to fire at a fixed
rate based on the Qtime clock.

This patch introduces ipa_qtime_config(), which configures the Qtime
mechanism for use.  It also adds to the IPA register definitions
related to timers and time stamping.

Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ipa/ipa_main.c | 67 +++++++++++++++++++++++++++++++++++---
 drivers/net/ipa/ipa_reg.h  | 30 +++++++++++++++++
 2 files changed, 93 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
index f25bcfe51dd4b..d0768452c15cf 100644
--- a/drivers/net/ipa/ipa_main.c
+++ b/drivers/net/ipa/ipa_main.c
@@ -70,6 +70,14 @@
 #define IPA_FWS_PATH		"ipa_fws.mdt"
 #define IPA_PAS_ID		15
 
+/* Shift of 19.2 MHz timestamp to achieve lower resolution timestamps */
+#define DPL_TIMESTAMP_SHIFT	14	/* ~1.172 kHz, ~853 usec per tick */
+#define TAG_TIMESTAMP_SHIFT	14
+#define NAT_TIMESTAMP_SHIFT	24	/* ~1.144 Hz, ~874 msec per tick */
+
+/* Divider for 19.2 MHz crystal oscillator clock to get common timer clock */
+#define IPA_XO_CLOCK_DIVIDER	192	/* 1 is subtracted where used */
+
 /**
  * ipa_suspend_handler() - Handle the suspend IPA interrupt
  * @ipa:	IPA pointer
@@ -292,6 +300,53 @@ static void ipa_hardware_config_qsb(struct ipa *ipa)
 	iowrite32(val, ipa->reg_virt + IPA_REG_QSB_MAX_READS_OFFSET);
 }
 
+/* IPA uses unified Qtime starting at IPA v4.5, implementing various
+ * timestamps and timers independent of the IPA core clock rate.  The
+ * Qtimer is based on a 56-bit timestamp incremented at each tick of
+ * a 19.2 MHz SoC crystal oscillator (XO clock).
+ *
+ * For IPA timestamps (tag, NAT, data path logging) a lower resolution
+ * timestamp is achieved by shifting the Qtimer timestamp value right
+ * some number of bits to produce the low-order bits of the coarser
+ * granularity timestamp.
+ *
+ * For timers, a common timer clock is derived from the XO clock using
+ * a divider (we use 192, to produce a 100kHz timer clock).  From
+ * this common clock, three "pulse generators" are used to produce
+ * timer ticks at a configurable frequency.  IPA timers (such as
+ * those used for aggregation or head-of-line block handling) now
+ * define their period based on one of these pulse generators.
+ */
+static void ipa_qtime_config(struct ipa *ipa)
+{
+	u32 val;
+
+	/* Timer clock divider must be disabled when we change the rate */
+	iowrite32(0, ipa->reg_virt + IPA_REG_TIMERS_XO_CLK_DIV_CFG_OFFSET);
+
+	/* Set DPL time stamp resolution to use Qtime (instead of 1 msec) */
+	val = u32_encode_bits(DPL_TIMESTAMP_SHIFT, DPL_TIMESTAMP_LSB_FMASK);
+	val |= u32_encode_bits(1, DPL_TIMESTAMP_SEL_FMASK);
+	/* Configure tag and NAT Qtime timestamp resolution as well */
+	val |= u32_encode_bits(TAG_TIMESTAMP_SHIFT, TAG_TIMESTAMP_LSB_FMASK);
+	val |= u32_encode_bits(NAT_TIMESTAMP_SHIFT, NAT_TIMESTAMP_LSB_FMASK);
+	iowrite32(val, ipa->reg_virt + IPA_REG_QTIME_TIMESTAMP_CFG_OFFSET);
+
+	/* Set granularity of pulse generators used for other timers */
+	val = u32_encode_bits(IPA_GRAN_100_US, GRAN_0_FMASK);
+	val |= u32_encode_bits(IPA_GRAN_1_MS, GRAN_1_FMASK);
+	val |= u32_encode_bits(IPA_GRAN_1_MS, GRAN_2_FMASK);
+	iowrite32(val, ipa->reg_virt + IPA_REG_TIMERS_PULSE_GRAN_CFG_OFFSET);
+
+	/* Actual divider is 1 more than value supplied here */
+	val = u32_encode_bits(IPA_XO_CLOCK_DIVIDER - 1, DIV_VALUE_FMASK);
+	iowrite32(val, ipa->reg_virt + IPA_REG_TIMERS_XO_CLK_DIV_CFG_OFFSET);
+
+	/* Divider value is set; re-enable the common timer clock divider */
+	val |= u32_encode_bits(1, DIV_ENABLE_FMASK);
+	iowrite32(val, ipa->reg_virt + IPA_REG_TIMERS_XO_CLK_DIV_CFG_OFFSET);
+}
+
 static void ipa_idle_indication_cfg(struct ipa *ipa,
 				    u32 enter_idle_debounce_thresh,
 				    bool const_non_idle_enable)
@@ -362,10 +417,14 @@ static void ipa_hardware_config(struct ipa *ipa)
 	/* Configure system bus limits */
 	ipa_hardware_config_qsb(ipa);
 
-	/* Configure aggregation granularity */
-	granularity = ipa_aggr_granularity_val(IPA_AGGR_GRANULARITY);
-	val = u32_encode_bits(granularity, AGGR_GRANULARITY_FMASK);
-	iowrite32(val, ipa->reg_virt + IPA_REG_COUNTER_CFG_OFFSET);
+	if (version < IPA_VERSION_4_5) {
+		/* Configure aggregation timer granularity */
+		granularity = ipa_aggr_granularity_val(IPA_AGGR_GRANULARITY);
+		val = u32_encode_bits(granularity, AGGR_GRANULARITY_FMASK);
+		iowrite32(val, ipa->reg_virt + IPA_REG_COUNTER_CFG_OFFSET);
+	} else {
+		ipa_qtime_config(ipa);
+	}
 
 	/* IPA v4.2 does not support hashed tables, so disable them */
 	if (version == IPA_VERSION_4_2) {
diff --git a/drivers/net/ipa/ipa_reg.h b/drivers/net/ipa/ipa_reg.h
index 09dcfa2998f04..e6b0827a244ec 100644
--- a/drivers/net/ipa/ipa_reg.h
+++ b/drivers/net/ipa/ipa_reg.h
@@ -223,6 +223,7 @@ static inline u32 ipa_reg_bcr_val(enum ipa_version version)
 /* ipa->available defines the valid bits in the AGGR_FORCE_CLOSE register */
 #define IPA_REG_AGGR_FORCE_CLOSE_OFFSET			0x000001ec
 
+/* The next register is not present for IPA v4.5 */
 #define IPA_REG_COUNTER_CFG_OFFSET			0x000001f0
 #define AGGR_GRANULARITY_FMASK			GENMASK(8, 4)
 
@@ -274,6 +275,35 @@ static inline u32 ipa_reg_idle_indication_cfg_offset(enum ipa_version version)
 #define ENTER_IDLE_DEBOUNCE_THRESH_FMASK	GENMASK(15, 0)
 #define CONST_NON_IDLE_ENABLE_FMASK		GENMASK(16, 16)
 
+/* The next register is present for IPA v4.5 */
+#define IPA_REG_QTIME_TIMESTAMP_CFG_OFFSET		0x0000024c
+#define DPL_TIMESTAMP_LSB_FMASK			GENMASK(4, 0)
+#define DPL_TIMESTAMP_SEL_FMASK			GENMASK(7, 7)
+#define TAG_TIMESTAMP_LSB_FMASK			GENMASK(12, 8)
+#define NAT_TIMESTAMP_LSB_FMASK			GENMASK(20, 16)
+
+/* The next register is present for IPA v4.5 */
+#define IPA_REG_TIMERS_XO_CLK_DIV_CFG_OFFSET		0x00000250
+#define DIV_VALUE_FMASK				GENMASK(8, 0)
+#define DIV_ENABLE_FMASK			GENMASK(31, 31)
+
+/* The next register is present for IPA v4.5 */
+#define IPA_REG_TIMERS_PULSE_GRAN_CFG_OFFSET		0x00000254
+#define GRAN_0_FMASK				GENMASK(2, 0)
+#define GRAN_1_FMASK				GENMASK(5, 3)
+#define GRAN_2_FMASK				GENMASK(8, 6)
+/* Values for GRAN_x fields of TIMERS_PULSE_GRAN_CFG */
+enum ipa_pulse_gran {
+	IPA_GRAN_10_US				= 0x0,
+	IPA_GRAN_20_US				= 0x1,
+	IPA_GRAN_50_US				= 0x2,
+	IPA_GRAN_100_US				= 0x3,
+	IPA_GRAN_1_MS				= 0x4,
+	IPA_GRAN_10_MS				= 0x5,
+	IPA_GRAN_100_MS				= 0x6,
+	IPA_GRAN_655350_US			= 0x7,
+};
+
 /* # IPA source resource groups available based on version */
 static inline u32 ipa_resource_group_src_count(enum ipa_version version)
 {
-- 
2.20.1

[PATCH net-next 3/4] net: ipa: use Qtime for IPA v4.5 aggregation time limit

[Alex Elder]

Change aggr_time_limit_encoded() to properly calculate the
aggregation time limit to use for IPA v4.5.

Older IPA versions program the AGGR_GRANULARITY field of the
of the COUNTER_CFG register to set the granularity of the
aggregation timer, which we configure to be 500 microseconds.

Instead, IPA v4.5 selects between two possible granularity values
derived from the 19.2 MHz Qtime clock.  These granularities are
100 microseconds or 1 millisecond per tick.  We use the smaller
granularity if possible, unless the desired period is too large
to be specified that way.

Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ipa/ipa_endpoint.c | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
index f260c80f50649..b4c884ccb77d2 100644
--- a/drivers/net/ipa/ipa_endpoint.c
+++ b/drivers/net/ipa/ipa_endpoint.c
@@ -638,14 +638,38 @@ static u32 aggr_byte_limit_encoded(enum ipa_version version, u32 limit)
 	return u32_encode_bits(limit, aggr_byte_limit_fmask(false));
 }
 
+/* Encode the aggregation timer limit (microseconds) based on IPA version */
 static u32 aggr_time_limit_encoded(enum ipa_version version, u32 limit)
 {
-	/* Convert limit (microseconds) to aggregation timer ticks */
-	limit = DIV_ROUND_CLOSEST(limit, IPA_AGGR_GRANULARITY);
-	if (version < IPA_VERSION_4_5)
+	u32 gran_sel;
+	u32 fmask;
+	u32 val;
+
+	if (version < IPA_VERSION_4_5) {
+		/* We set aggregation granularity in ipa_hardware_config() */
+		limit = DIV_ROUND_CLOSEST(limit, IPA_AGGR_GRANULARITY);
+
 		return u32_encode_bits(limit, aggr_time_limit_fmask(true));
+	}
 
-	return u32_encode_bits(limit, aggr_time_limit_fmask(false));
+	/* IPA v4.5 expresses the time limit using Qtime.  The AP has
+	 * pulse generators 0 and 1 available, which were configured
+	 * in ipa_qtime_config() to have granularity 100 usec and
+	 * 1 msec, respectively.  Use pulse generator 0 if possible,
+	 * otherwise fall back to pulse generator 1.
+	 */
+	fmask = aggr_time_limit_fmask(false);
+	val = DIV_ROUND_CLOSEST(limit, 100);
+	if (val > field_max(fmask)) {
+		/* Have to use pulse generator 1 (millisecond granularity) */
+		gran_sel = AGGR_GRAN_SEL_FMASK;
+		val = DIV_ROUND_CLOSEST(limit, 1000);
+	} else {
+		/* We can use pulse generator 0 (100 usec granularity) */
+		gran_sel = 0;
+	}
+
+	return gran_sel | u32_encode_bits(val, fmask);
 }
 
 static u32 aggr_sw_eof_active_encoded(enum ipa_version version, bool enabled)
-- 
2.20.1

[PATCH net-next 4/4] net: ipa: use Qtime for IPA v4.5 head-of-line time limit

[Alex Elder]

Extend ipa_reg_init_hol_block_timer_val() so it properly calculates
the head-of-line block timeout to use for IPA v4.5.

Introduce hol_block_timer_qtime_val() to compute the value to use
for IPA v4.5, where Qtime is used as the basis of the timer.  Call
that function from hol_block_timer_val() for IPA v4.5.

Both of these are private functions, so shorten their names a bit so
they don't take up so much space on the line.

Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ipa/ipa_endpoint.c | 48 +++++++++++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
index b4c884ccb77d2..9f4be9812a1f3 100644
--- a/drivers/net/ipa/ipa_endpoint.c
+++ b/drivers/net/ipa/ipa_endpoint.c
@@ -724,12 +724,45 @@ static void ipa_endpoint_init_aggr(struct ipa_endpoint *endpoint)
 	iowrite32(val, endpoint->ipa->reg_virt + offset);
 }
 
-/* The head-of-line blocking timer is defined as a tick count, where each
- * tick represents 128 cycles of the IPA core clock.  Return the value
- * that should be written to that register that represents the timeout
- * period provided.
+/* Return the Qtime-based head-of-line blocking timer value that
+ * represents the given number of microseconds.  The result
+ * includes both the timer value and the selected timer granularity.
  */
-static u32 ipa_reg_init_hol_block_timer_val(struct ipa *ipa, u32 microseconds)
+static u32 hol_block_timer_qtime_val(struct ipa *ipa, u32 microseconds)
+{
+	u32 gran_sel;
+	u32 val;
+
+	/* IPA v4.5 expresses time limits using Qtime.  The AP has
+	 * pulse generators 0 and 1 available, which were configured
+	 * in ipa_qtime_config() to have granularity 100 usec and
+	 * 1 msec, respectively.  Use pulse generator 0 if possible,
+	 * otherwise fall back to pulse generator 1.
+	 */
+	val = DIV_ROUND_CLOSEST(microseconds, 100);
+	if (val > field_max(TIME_LIMIT_FMASK)) {
+		/* Have to use pulse generator 1 (millisecond granularity) */
+		gran_sel = GRAN_SEL_FMASK;
+		val = DIV_ROUND_CLOSEST(microseconds, 1000);
+	} else {
+		/* We can use pulse generator 0 (100 usec granularity) */
+		gran_sel = 0;
+	}
+
+	return gran_sel | u32_encode_bits(val, TIME_LIMIT_FMASK);
+}
+
+/* The head-of-line blocking timer is defined as a tick count.  For
+ * IPA version 4.5 the tick count is based on the Qtimer, which is
+ * derived from the 19.2 MHz SoC XO clock.  For older IPA versions
+ * each tick represents 128 cycles of the IPA core clock.
+ *
+ * Return the encoded value that should be written to that register
+ * that represents the timeout period provided.  For IPA v4.2 this
+ * encodes a base and scale value, while for earlier versions the
+ * value is a simple tick count.
+ */
+static u32 hol_block_timer_val(struct ipa *ipa, u32 microseconds)
 {
 	u32 width;
 	u32 scale;
@@ -741,6 +774,9 @@ static u32 ipa_reg_init_hol_block_timer_val(struct ipa *ipa, u32 microseconds)
 	if (!microseconds)
 		return 0;	/* Nothing to compute if timer period is 0 */
 
+	if (ipa->version == IPA_VERSION_4_5)
+		return hol_block_timer_qtime_val(ipa, microseconds);
+
 	/* Use 64 bit arithmetic to avoid overflow... */
 	rate = ipa_clock_rate(ipa);
 	ticks = DIV_ROUND_CLOSEST(microseconds * rate, 128 * USEC_PER_SEC);
@@ -786,7 +822,7 @@ static void ipa_endpoint_init_hol_block_timer(struct ipa_endpoint *endpoint,
 	u32 val;
 
 	offset = IPA_REG_ENDP_INIT_HOL_BLOCK_TIMER_N_OFFSET(endpoint_id);
-	val = ipa_reg_init_hol_block_timer_val(ipa, microseconds);
+	val = hol_block_timer_val(ipa, microseconds);
 	iowrite32(val, ipa->reg_virt + offset);
 }
 
-- 
2.20.1

Re: [PATCH net-next 0/4] net: ipa: IPA v4.5 aggregation and Qtime

[Jakub Kicinski]

On Mon, 30 Nov 2020 17:37:08 -0600 Alex Elder wrote:
> This series updates some IPA register definitions that change in
> substantive ways for IPA v4.5.
> 
> One register defines parameters used by an endpoint to aggregate
> multiple packets into a buffer.  The size and position of most
> fields in that register have changed with this new hardware version,
> and consequently the function that programs it needs to be done a
> bit differently.  The first patch takes care of this.
> 
> Second, IPA v4.5 introduces a unified time keeping component to be
> used in several places by the IPA hardware.  A main clock divider
> provides a fundamental tick rate, and several timestamped features 
> now define their granularity based on that.  There is also a set of
> "pulse generators" derived from the main tick, and these are used
> to implement timers used for aggregation and head-of-line block
> avoidance.  The second patch adds IPA register updates to support
> Qtime along with its configuration, and the last two patches
> configure the timers that use it.

Applied, thanks!