Merge branch 'net-stmmac-correct-mac-propagation-delay'

Johannes Zink says:

====================
net: stmmac: correct MAC propagation delay

Changes in v3:
- work in Richard's review feedback. Thank you for reviewing my patch:
  - as some of the hardware may have no or invalid correction value
    registers: introduce feature switch which can be enabled in the glue
    code drivers depending on the actual hardware support
  - only enable the feature on the i.MX8MP for the time being, as the patch
    improves timing accuracy and is tested for this hardware
- Link to v2: https://lore.kernel.org/r/20230719-stmmac_correct_mac_delay-v2-1-3366f38ee9a6@pengutronix.de

Changes in v2:
- fix builds for 32bit, this was found by the kernel build bot
	Reported-by: kernel test robot <lkp@intel.com>
	Closes: https://lore.kernel.org/oe-kbuild-all/202307200225.B8rmKQPN-lkp@intel.com/
- while at it also fix an overflow by shifting a u32 constant from macro by 10bits
  by casting the constant to u64
- Link to v1: https://lore.kernel.org/r/20230719-stmmac_correct_mac_delay-v1-1-768aa4d09334@pengutronix.de

Tested-by: Kurt Kanzenbach <kurt@linutronix.de> # imx8mp
====================

Link: https://lore.kernel.org/r/20230719-stmmac_correct_mac_delay-v3-0-61e63427735e@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

6 files changed, 64 insertions, 0 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
index 92e06a96757a..645a9454a490 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
@@ -42,6 +42,7 @@
 
 struct imx_dwmac_ops {
 	u32 addr_width;
+	u32 flags;
 	bool mac_rgmii_txclk_auto_adj;
 
 	int (*fix_soc_reset)(void *priv, void __iomem *ioaddr);
@@ -311,6 +312,9 @@ static int imx_dwmac_probe(struct platform_device *pdev)
 		goto err_parse_dt;
 	}
 
+	if (data->flags & STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY)
+		plat_dat->flags |= STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY;
+
 	plat_dat->host_dma_width = dwmac->ops->addr_width;
 	plat_dat->init = imx_dwmac_init;
 	plat_dat->exit = imx_dwmac_exit;
@@ -350,6 +354,7 @@ static struct imx_dwmac_ops imx8mp_dwmac_data = {
 	.addr_width = 34,
 	.mac_rgmii_txclk_auto_adj = false,
 	.set_intf_mode = imx8mp_set_intf_mode,
+	.flags = STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY,
 };
 
 static struct imx_dwmac_ops imx8dxl_dwmac_data = {
diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.h b/drivers/net/ethernet/stmicro/stmmac/hwif.h
index 652af8f6e75f..238f17c50a1e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/hwif.h
+++ b/drivers/net/ethernet/stmicro/stmmac/hwif.h
@@ -532,6 +532,7 @@ struct stmmac_hwtimestamp {
 	void (*get_systime) (void __iomem *ioaddr, u64 *systime);
 	void (*get_ptptime)(void __iomem *ioaddr, u64 *ptp_time);
 	void (*timestamp_interrupt)(struct stmmac_priv *priv);
+	void (*hwtstamp_correct_latency)(struct stmmac_priv *priv);
 };
 
 #define stmmac_config_hw_tstamping(__priv, __args...) \
@@ -550,6 +551,8 @@ struct stmmac_hwtimestamp {
 	stmmac_do_void_callback(__priv, ptp, get_ptptime, __args)
 #define stmmac_timestamp_interrupt(__priv, __args...) \
 	stmmac_do_void_callback(__priv, ptp, timestamp_interrupt, __args)
+#define stmmac_hwtstamp_correct_latency(__priv, __args...) \
+	stmmac_do_void_callback(__priv, ptp, hwtstamp_correct_latency, __args)
 
 struct stmmac_tx_queue;
 struct stmmac_rx_queue;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
index fa2c3ba7e9fe..540f6a4ec0b8 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
@@ -60,6 +60,48 @@ static void config_sub_second_increment(void __iomem *ioaddr,
 		*ssinc = data;
 }
 
+static void hwtstamp_correct_latency(struct stmmac_priv *priv)
+{
+	void __iomem *ioaddr = priv->ptpaddr;
+	u32 reg_tsic, reg_tsicsns;
+	u32 reg_tsec, reg_tsecsns;
+	u64 scaled_ns;
+	u32 val;
+
+	/* MAC-internal ingress latency */
+	scaled_ns = readl(ioaddr + PTP_TS_INGR_LAT);
+
+	/* See section 11.7.2.5.3.1 "Ingress Correction" on page 4001 of
+	 * i.MX8MP Applications Processor Reference Manual Rev. 1, 06/2021
+	 */
+	val = readl(ioaddr + PTP_TCR);
+	if (val & PTP_TCR_TSCTRLSSR)
+		/* nanoseconds field is in decimal format with granularity of 1ns/bit */
+		scaled_ns = ((u64)NSEC_PER_SEC << 16) - scaled_ns;
+	else
+		/* nanoseconds field is in binary format with granularity of ~0.466ns/bit */
+		scaled_ns = ((1ULL << 31) << 16) -
+			DIV_U64_ROUND_CLOSEST(scaled_ns * PSEC_PER_NSEC, 466U);
+
+	reg_tsic = scaled_ns >> 16;
+	reg_tsicsns = scaled_ns & 0xff00;
+
+	/* set bit 31 for 2's compliment */
+	reg_tsic |= BIT(31);
+
+	writel(reg_tsic, ioaddr + PTP_TS_INGR_CORR_NS);
+	writel(reg_tsicsns, ioaddr + PTP_TS_INGR_CORR_SNS);
+
+	/* MAC-internal egress latency */
+	scaled_ns = readl(ioaddr + PTP_TS_EGR_LAT);
+
+	reg_tsec = scaled_ns >> 16;
+	reg_tsecsns = scaled_ns & 0xff00;
+
+	writel(reg_tsec, ioaddr + PTP_TS_EGR_CORR_NS);
+	writel(reg_tsecsns, ioaddr + PTP_TS_EGR_CORR_SNS);
+}
+
 static int init_systime(void __iomem *ioaddr, u32 sec, u32 nsec)
 {
 	u32 value;
@@ -221,4 +263,5 @@ const struct stmmac_hwtimestamp stmmac_ptp = {
 	.get_systime = get_systime,
 	.get_ptptime = get_ptptime,
 	.timestamp_interrupt = timestamp_interrupt,
+	.hwtstamp_correct_latency = hwtstamp_correct_latency,
 };
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index e1f1c034d325..99aa5360b3ff 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -909,6 +909,9 @@ static int stmmac_init_ptp(struct stmmac_priv *priv)
 	priv->hwts_tx_en = 0;
 	priv->hwts_rx_en = 0;
 
+	if (priv->plat->flags & STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY)
+		stmmac_hwtstamp_correct_latency(priv, priv);
+
 	return 0;
 }
 
@@ -1094,6 +1097,9 @@ static void stmmac_mac_link_up(struct phylink_config *config,
 
 	if (priv->dma_cap.fpesel)
 		stmmac_fpe_link_state_handle(priv, true);
+
+	if (priv->plat->flags & STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY)
+		stmmac_hwtstamp_correct_latency(priv, priv);
 }
 
 static const struct phylink_mac_ops stmmac_phylink_mac_ops = {
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h
index bf619295d079..d1fe4b46f162 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h
@@ -26,6 +26,12 @@
 #define	PTP_ACR		0x40	/* Auxiliary Control Reg */
 #define	PTP_ATNR	0x48	/* Auxiliary Timestamp - Nanoseconds Reg */
 #define	PTP_ATSR	0x4c	/* Auxiliary Timestamp - Seconds Reg */
+#define	PTP_TS_INGR_CORR_NS	0x58	/* Ingress timestamp correction nanoseconds */
+#define	PTP_TS_EGR_CORR_NS	0x5C	/* Egress timestamp correction nanoseconds*/
+#define	PTP_TS_INGR_CORR_SNS	0x60	/* Ingress timestamp correction subnanoseconds */
+#define	PTP_TS_EGR_CORR_SNS	0x64	/* Egress timestamp correction subnanoseconds */
+#define	PTP_TS_INGR_LAT	0x68	/* MAC internal Ingress Latency */
+#define	PTP_TS_EGR_LAT	0x6c	/* MAC internal Egress Latency */
 
 #define	PTP_STNSUR_ADDSUB_SHIFT	31
 #define	PTP_DIGITAL_ROLLOVER_MODE	0x3B9ACA00	/* 10e9-1 ns */
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index 3d0702510224..652404c03944 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -218,6 +218,7 @@ struct dwmac4_addrs {
 #define STMMAC_FLAG_INT_SNAPSHOT_EN		BIT(9)
 #define STMMAC_FLAG_RX_CLK_RUNS_IN_LPI		BIT(10)
 #define STMMAC_FLAG_EN_TX_LPI_CLOCKGATING	BIT(11)
+#define STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY	BIT(12)
 
 struct plat_stmmacenet_data {
 	int bus_id;