[PATCH net-next v4 7/8] r8152: extract rtl_fc_pause_pkt_en() and apply it to RTL8156/8157/8159

[Chih Kai Hsu <hsu.chih.kai@realtek.com>]

The flow-control patch in r8156b_init() only ran for RTL8156B
(VER_12/13/15). RTL8156A (VER_10/11) and RTL8157/RTL8159 (VER_16/17)
never applied any flow-control patch at all.

Extract it into rtl_fc_pause_pkt_en(tp, speed) and add the missing
cases:

- VER_10/11: same FC timer + FLOW_CTRL_PATCH_OPT sequence RTL8153B
  (VER_09) already applies via its pre_fw/post_fw hooks, applied
  directly here instead.

- VER_16/17_QFN68/QFN100: RTL8157/RTL8159 use a different mechanism.
  The datasheet gives a fixed pause-packet count per link speed via
  the new PLA_PAUSE_LIMIT register; num_pause_pkts is computed with
  a log2-ratio formula that reproduces that table. Since the count
  depends on the negotiated speed, call rtl_fc_pause_pkt_en() from
  rtl8157_enable() instead of from init.

Signed-off-by: Chih Kai Hsu <hsu.chih.kai@realtek.com>
---
 drivers/net/usb/r8152.c | 112 ++++++++++++++++++++++++++++++++++------
 1 file changed, 97 insertions(+), 15 deletions(-)

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 3473061af129a..05b2b79ab3e31 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -89,6 +89,7 @@
 #define PLA_MTPS		0xe615
 #define PLA_TXFIFO_CTRL		0xe618
 #define PLA_TXFIFO_FULL		0xe61a
+#define PLA_PAUSE_LIMIT         0xe61e
 #define PLA_RSTTALLY		0xe800
 #define PLA_CR			0xe813
 #define PLA_CRWECR		0xe81c
@@ -301,6 +302,10 @@
 #define MTPS_JUMBO		(12 * 1024 / 64)
 #define MTPS_DEFAULT		(6 * 1024 / 64)
 
+/* PLA_PAUSE_LIMIT */
+#define PAUSE_LIMIT_EN		BIT(3)
+#define PAUSE_LIMIT_MASK	0xf0
+
 /* PLA_RSTTALLY */
 #define TALLY_RESET		0x0001
 
@@ -6163,6 +6168,93 @@ static void r8152b_enter_oob(struct r8152 *tp)
 			   RCR_APM | RCR_AM | RCR_AB);
 }
 
+static void rtl_fc_pause_pkt_en(struct r8152 *tp, u16 speed)
+{
+	int log2_ratio, ratio;
+	u16 num_pause_pkts;
+	u32 ocp_data;
+
+	switch (tp->version) {
+	case RTL_VER_10:
+	case RTL_VER_11:
+		ocp_write_word(tp, MCU_TYPE_USB, USB_FC_TIMER,
+			       CTRL_TIMER_EN | (1000 / 8));
+
+		ocp_word_set_bits(tp, MCU_TYPE_USB, USB_FW_CTRL,
+				  FLOW_CTRL_PATCH_OPT);
+
+		ocp_word_set_bits(tp, MCU_TYPE_USB, USB_FW_TASK, FC_PATCH_TASK);
+		break;
+	case RTL_VER_12:
+	case RTL_VER_13:
+	case RTL_VER_15:
+		ocp_word_clr_bits(tp, MCU_TYPE_PLA, PLA_RCR, SLOT_EN);
+
+		ocp_word_set_bits(tp, MCU_TYPE_PLA, PLA_CPCR, FLOW_CTRL_EN);
+
+		/* enable fc timer and set timer to 600 ms. */
+		ocp_write_word(tp, MCU_TYPE_USB, USB_FC_TIMER,
+			       CTRL_TIMER_EN | (600 / 8));
+
+		ocp_data = ocp_read_word(tp, MCU_TYPE_PLA, PLA_POL_GPIO_CTRL);
+		if (!(ocp_data & DACK_DET_EN))
+			ocp_word_set_bits(tp, MCU_TYPE_USB, USB_FW_CTRL,
+					  FLOW_CTRL_PATCH_2);
+
+		ocp_word_set_bits(tp, MCU_TYPE_USB, USB_FW_TASK, FC_PATCH_TASK);
+		break;
+	case RTL_VER_16:
+	case RTL_VER_17_QFN68:
+	case RTL_VER_17_QFN100:
+		ocp_word_clr_bits(tp, MCU_TYPE_PLA, PLA_RCR, SLOT_EN);
+
+		num_pause_pkts = 0xa;
+		ratio = 10000;
+
+		if (!(speed & LINK_STATUS)) {
+			dev_dbg(&tp->intf->dev, "No link\n");
+			goto no_link;
+		} else if (speed & _10bps) {
+			ratio /= 10;
+		} else if (speed & _100bps) {
+			ratio /= 100;
+		} else if (speed & _1000bps) {
+			ratio /= 1000;
+		} else if (speed & _2500bps) {
+			ratio /= 2500;
+		} else if (speed & _5000bps) {
+			ratio /= 5000;
+		} else if (speed & _10000bps) {
+			ratio /= 10000;
+		} else {
+			dev_err(&tp->intf->dev, "Unknown link speed\n");
+			goto no_link;
+		}
+
+		log2_ratio = ilog2(ratio);
+		num_pause_pkts -= log2_ratio;
+
+		/* Round up if ratio is more than halfway to the next power of 2.
+		 * Floating-point is avoided by rewriting
+		 * ratio > 1.5 * 2^log2_ratio as
+		 * 2 * ratio > 3 * 2^log2_ratio
+		 */
+		if (2 * ratio > 3 * (1 << log2_ratio))
+			num_pause_pkts--;
+
+no_link:
+		ocp_word_w0w1(tp, MCU_TYPE_PLA, PLA_PAUSE_LIMIT,
+			      PAUSE_LIMIT_MASK | PAUSE_LIMIT_EN,
+			      num_pause_pkts << 4);
+
+		ocp_word_set_bits(tp, MCU_TYPE_PLA, PLA_PAUSE_LIMIT,
+				  PAUSE_LIMIT_EN);
+		break;
+	default:
+		break;
+	}
+}
+
 static int r8153_pre_firmware_1(struct r8152 *tp)
 {
 	int i;
@@ -6694,6 +6786,8 @@ static int rtl8157_enable(struct r8152 *tp)
 	r8153_set_rx_early_size(tp);
 
 	speed = rtl8152_get_speed(tp);
+	rtl_fc_pause_pkt_en(tp, speed);
+
 	rtl_set_ifg(tp, speed);
 
 	return rtl_enable(tp);
@@ -8842,6 +8936,8 @@ static void r8156_init(struct r8152 *tp)
 
 	usb_enable_lpm(tp->udev);
 
+	rtl_fc_pause_pkt_en(tp, 0);
+
 	r8156_mac_clk_spd(tp, true);
 
 	ocp_word_clr_bits(tp, MCU_TYPE_PLA, PLA_MAC_PWR_CTRL3,
@@ -8878,7 +8974,6 @@ static void r8156b_u2phy_backup(struct r8152 *tp)
 
 static void r8156b_init(struct r8152 *tp)
 {
-	u32 ocp_data;
 	u16 data;
 
 	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
@@ -8943,20 +9038,7 @@ static void r8156b_init(struct r8152 *tp)
 
 	usb_enable_lpm(tp->udev);
 
-	ocp_word_clr_bits(tp, MCU_TYPE_PLA, PLA_RCR, SLOT_EN);
-
-	ocp_word_set_bits(tp, MCU_TYPE_PLA, PLA_CPCR, FLOW_CTRL_EN);
-
-	/* enable fc timer and set timer to 600 ms. */
-	ocp_write_word(tp, MCU_TYPE_USB, USB_FC_TIMER,
-		       CTRL_TIMER_EN | (600 / 8));
-
-	ocp_data = ocp_read_word(tp, MCU_TYPE_PLA, PLA_POL_GPIO_CTRL);
-	if (!(ocp_data & DACK_DET_EN))
-		ocp_word_set_bits(tp, MCU_TYPE_USB, USB_FW_CTRL,
-				  FLOW_CTRL_PATCH_2);
-
-	ocp_word_set_bits(tp, MCU_TYPE_USB, USB_FW_TASK, FC_PATCH_TASK);
+	rtl_fc_pause_pkt_en(tp, 0);
 
 	r8156_mac_clk_spd(tp, true);
 
-- 
2.34.1