Merge branch 'net-ipa-ipa-v4-5-aggregation-and-qtime'

Alex Elder says:

====================
net: ipa: IPA v4.5 aggregation and Qtime

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.
====================

Link: https://lore.kernel.org/r/20201130233712.29113-1-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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)
@@ -180,21 +155,51 @@ 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",
 			count, IPA_ENDPOINT_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 +629,84 @@ 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));
+}
+
+/* Encode the aggregation timer limit (microseconds) based on IPA version */
+static u32 aggr_time_limit_encoded(enum ipa_version version, u32 limit)
+{
+	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));
+	}
+
+	/* 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)
+{
+	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,
@@ -664,12 +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 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 ipa_reg_init_hol_block_timer_val(struct ipa *ipa, u32 microseconds)
+static u32 hol_block_timer_val(struct ipa *ipa, u32 microseconds)
 {
 	u32 width;
 	u32 scale;
@@ -681,6 +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);
@@ -726,7 +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);
 }
 

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) {