Merge branch 'altera-tse-phylink'

Maxime Chevallier says:

====================
net: altera: tse: phylink conversion

This is V4 of a series converting the Altera TSE driver to phylink,
introducing a new PCS driver along the way.

The Altera TSE can be built with a SGMII/1000BaseX PCS, allowing to use
SFP ports with this MAC, which is the end goal of adding phylink support
and a proper PCS driver.

The PCS itself can either be mapped in the MAC's register space, in that
case, it's accessed through 32 bits registers, with the higher 16 bits
always 0. Alternatively, it can sit on its own register space, exposing
16 bits registers, some of which ressemble the standard PHY registers.

To tackle that rework, several things needs updating, starting by the DT
binding, since we add support for a new register range for the PCS.

Hence, the first patch of the series is a conversion to YAML of the
existing binding.

Then, patch 2 does a bit of simple cleanup to the TSE driver, using nice
reverse xmas tree definitions.

Patch 3 adds the actual PCS driver, as a standalone driver. Some future
series will then reuse that PCS driver from the dwmac-socfpga driver,
which implements support for this exact PCS too, allowing to share the
code nicely.

Patch 4 is then a phylink conversion of the altera_tse driver, to use
this new PCS driver.

Finally, patch 5 updates the newly converted DT binding to support the
pcs register range.

This series contains bits and pieces for this conversion, please tell me if
you want me to send it as individual patches.

V4 Changes:
 - Add missing MODULE_* macros to the TSE PCS driver

V3 Changes:
 - YAML binding conversion changes and PCS addition changes thanks to
   Krzysztof's reviews

V2 Changes :
 - Fixed the binding after the YAML conversion
 - Added a pcs_validate() callback
 - Introduced a comment to justify a soft reset for the PCS
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 175 insertions, 0 deletions

diff --git a/drivers/net/pcs/pcs-altera-tse.c b/drivers/net/pcs/pcs-altera-tse.c
new file mode 100644
index 000000000000..97a7cabff962
--- /dev/null
+++ b/drivers/net/pcs/pcs-altera-tse.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Bootlin
+ *
+ * Maxime Chevallier <maxime.chevallier@bootlin.com>
+ */
+
+#include <linux/netdevice.h>
+#include <linux/phy.h>
+#include <linux/phylink.h>
+#include <linux/pcs-altera-tse.h>
+
+/* SGMII PCS register addresses
+ */
+#define SGMII_PCS_SCRATCH	0x10
+#define SGMII_PCS_REV		0x11
+#define SGMII_PCS_LINK_TIMER_0	0x12
+#define   SGMII_PCS_LINK_TIMER_REG(x)		(0x12 + (x))
+#define SGMII_PCS_LINK_TIMER_1	0x13
+#define SGMII_PCS_IF_MODE	0x14
+#define   PCS_IF_MODE_SGMII_ENA		BIT(0)
+#define   PCS_IF_MODE_USE_SGMII_AN	BIT(1)
+#define   PCS_IF_MODE_SGMI_SPEED_MASK	GENMASK(3, 2)
+#define   PCS_IF_MODE_SGMI_SPEED_10	(0 << 2)
+#define   PCS_IF_MODE_SGMI_SPEED_100	(1 << 2)
+#define   PCS_IF_MODE_SGMI_SPEED_1000	(2 << 2)
+#define   PCS_IF_MODE_SGMI_HALF_DUPLEX	BIT(4)
+#define   PCS_IF_MODE_SGMI_PHY_AN	BIT(5)
+#define SGMII_PCS_DIS_READ_TO	0x15
+#define SGMII_PCS_READ_TO	0x16
+#define SGMII_PCS_SW_RESET_TIMEOUT 100 /* usecs */
+
+struct altera_tse_pcs {
+	struct phylink_pcs pcs;
+	void __iomem *base;
+	int reg_width;
+};
+
+static struct altera_tse_pcs *phylink_pcs_to_tse_pcs(struct phylink_pcs *pcs)
+{
+	return container_of(pcs, struct altera_tse_pcs, pcs);
+}
+
+static u16 tse_pcs_read(struct altera_tse_pcs *tse_pcs, int regnum)
+{
+	if (tse_pcs->reg_width == 4)
+		return readl(tse_pcs->base + regnum * 4);
+	else
+		return readw(tse_pcs->base + regnum * 2);
+}
+
+static void tse_pcs_write(struct altera_tse_pcs *tse_pcs, int regnum,
+			  u16 value)
+{
+	if (tse_pcs->reg_width == 4)
+		writel(value, tse_pcs->base + regnum * 4);
+	else
+		writew(value, tse_pcs->base + regnum * 2);
+}
+
+static int tse_pcs_reset(struct altera_tse_pcs *tse_pcs)
+{
+	int i = 0;
+	u16 bmcr;
+
+	/* Reset PCS block */
+	bmcr = tse_pcs_read(tse_pcs, MII_BMCR);
+	bmcr |= BMCR_RESET;
+	tse_pcs_write(tse_pcs, MII_BMCR, bmcr);
+
+	for (i = 0; i < SGMII_PCS_SW_RESET_TIMEOUT; i++) {
+		if (!(tse_pcs_read(tse_pcs, MII_BMCR) & BMCR_RESET))
+			return 0;
+		udelay(1);
+	}
+
+	return -ETIMEDOUT;
+}
+
+static int alt_tse_pcs_validate(struct phylink_pcs *pcs,
+				unsigned long *supported,
+				const struct phylink_link_state *state)
+{
+	if (state->interface == PHY_INTERFACE_MODE_SGMII ||
+	    state->interface == PHY_INTERFACE_MODE_1000BASEX)
+		return 1;
+
+	return -EINVAL;
+}
+
+static int alt_tse_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
+			      phy_interface_t interface,
+			      const unsigned long *advertising,
+			      bool permit_pause_to_mac)
+{
+	struct altera_tse_pcs *tse_pcs = phylink_pcs_to_tse_pcs(pcs);
+	u32 ctrl, if_mode;
+
+	ctrl = tse_pcs_read(tse_pcs, MII_BMCR);
+	if_mode = tse_pcs_read(tse_pcs, SGMII_PCS_IF_MODE);
+
+	/* Set link timer to 1.6ms, as per the MegaCore Function User Guide */
+	tse_pcs_write(tse_pcs, SGMII_PCS_LINK_TIMER_0, 0x0D40);
+	tse_pcs_write(tse_pcs, SGMII_PCS_LINK_TIMER_1, 0x03);
+
+	if (interface == PHY_INTERFACE_MODE_SGMII) {
+		if_mode |= PCS_IF_MODE_USE_SGMII_AN | PCS_IF_MODE_SGMII_ENA;
+	} else if (interface == PHY_INTERFACE_MODE_1000BASEX) {
+		if_mode &= ~(PCS_IF_MODE_USE_SGMII_AN | PCS_IF_MODE_SGMII_ENA);
+		if_mode |= PCS_IF_MODE_SGMI_SPEED_1000;
+	}
+
+	ctrl |= (BMCR_SPEED1000 | BMCR_FULLDPLX | BMCR_ANENABLE);
+
+	tse_pcs_write(tse_pcs, MII_BMCR, ctrl);
+	tse_pcs_write(tse_pcs, SGMII_PCS_IF_MODE, if_mode);
+
+	return tse_pcs_reset(tse_pcs);
+}
+
+static void alt_tse_pcs_get_state(struct phylink_pcs *pcs,
+				  struct phylink_link_state *state)
+{
+	struct altera_tse_pcs *tse_pcs = phylink_pcs_to_tse_pcs(pcs);
+	u16 bmsr, lpa;
+
+	bmsr = tse_pcs_read(tse_pcs, MII_BMSR);
+	lpa = tse_pcs_read(tse_pcs, MII_LPA);
+
+	phylink_mii_c22_pcs_decode_state(state, bmsr, lpa);
+}
+
+static void alt_tse_pcs_an_restart(struct phylink_pcs *pcs)
+{
+	struct altera_tse_pcs *tse_pcs = phylink_pcs_to_tse_pcs(pcs);
+	u16 bmcr;
+
+	bmcr = tse_pcs_read(tse_pcs, MII_BMCR);
+	bmcr |= BMCR_ANRESTART;
+	tse_pcs_write(tse_pcs, MII_BMCR, bmcr);
+
+	/* This PCS seems to require a soft reset to re-sync the AN logic */
+	tse_pcs_reset(tse_pcs);
+}
+
+static const struct phylink_pcs_ops alt_tse_pcs_ops = {
+	.pcs_validate = alt_tse_pcs_validate,
+	.pcs_get_state = alt_tse_pcs_get_state,
+	.pcs_config = alt_tse_pcs_config,
+	.pcs_an_restart = alt_tse_pcs_an_restart,
+};
+
+struct phylink_pcs *alt_tse_pcs_create(struct net_device *ndev,
+				       void __iomem *pcs_base, int reg_width)
+{
+	struct altera_tse_pcs *tse_pcs;
+
+	if (reg_width != 4 && reg_width != 2)
+		return ERR_PTR(-EINVAL);
+
+	tse_pcs = devm_kzalloc(&ndev->dev, sizeof(*tse_pcs), GFP_KERNEL);
+	if (!tse_pcs)
+		return ERR_PTR(-ENOMEM);
+
+	tse_pcs->pcs.ops = &alt_tse_pcs_ops;
+	tse_pcs->base = pcs_base;
+	tse_pcs->reg_width = reg_width;
+
+	return &tse_pcs->pcs;
+}
+EXPORT_SYMBOL_GPL(alt_tse_pcs_create);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Altera TSE PCS driver");
+MODULE_AUTHOR("Maxime Chevallier <maxime.chevallier@bootlin.com>");