linux-kernel - [PATCH 2/2] can: sja1000: of: add compatibility with Technologic Systems version

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Message-Id: <1450469845-12900-2-git-send-email-damien.riegel@savoirfairelinux.com>
Date:	Fri, 18 Dec 2015 15:17:25 -0500
From:	Damien Riegel <damien.riegel@...oirfairelinux.com>
To:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	linux-can@...r.kernel.org, devicetree@...r.kernel.org
Cc:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Wolfgang Grandegger <wg@...ndegger.com>,
	Marc Kleine-Budde <mkl@...gutronix.de>,
	kernel@...oirfairelinux.com,
	Damien Riegel <damien.riegel@...oirfairelinux.com>
Subject: [PATCH 2/2] can: sja1000: of: add compatibility with Technologic Systems version

Technologic Systems provides an IP compatible with the SJA1000,
instantiated in an FPGA. Because of some bus widths issue, access to
registers is made through a "window" that works like this:

    base + 0x0: address to read/write
    base + 0x2: 8-bit register value

This commit adds a new compatible device, "technologic,sja1000", with
read and write functions using the window mechanism.

Signed-off-by: Damien Riegel <damien.riegel@...oirfairelinux.com>
---
 drivers/net/can/sja1000/sja1000_platform.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/sja1000/sja1000_platform.c b/drivers/net/can/sja1000/sja1000_platform.c
index 0552ed4..6cbf251 100644
--- a/drivers/net/can/sja1000/sja1000_platform.c
+++ b/drivers/net/can/sja1000/sja1000_platform.c
@@ -70,6 +70,18 @@ static void sp_write_reg32(const struct sja1000_priv *priv, int reg, u8 val)
 	iowrite8(val, priv->reg_base + reg * 4);
 }
 
+static u8 ts4800_read_reg16(const struct sja1000_priv *priv, int reg)
+{
+	sp_write_reg16(priv, 0,  reg);
+	return sp_read_reg16(priv, 2);
+}
+
+static void ts4800_write_reg16(const struct sja1000_priv *priv, int reg, u8 val)
+{
+	sp_write_reg16(priv, 0, reg);
+	sp_write_reg16(priv, 2, val);
+}
+
 static void sp_populate(struct sja1000_priv *priv,
 			struct sja1000_platform_data *pdata,
 			unsigned long resource_mem_flags)
@@ -98,21 +110,34 @@ static void sp_populate(struct sja1000_priv *priv,
 
 static void sp_populate_of(struct sja1000_priv *priv, struct device_node *of)
 {
+	int is_technologic;
 	int err;
 	u32 prop;
 
+	is_technologic = of_device_is_compatible(of, "technologic,sja1000");
+
 	err = of_property_read_u32(of, "reg-io-width", &prop);
 	if (err)
 		prop = 1; /* 8 bit is default */
 
+	if (is_technologic && prop != 2) {
+		netdev_warn(priv->dev, "forcing reg-io-width to 2\n");
+		prop = 2;
+	}
+
 	switch (prop) {
 	case 4:
 		priv->read_reg = sp_read_reg32;
 		priv->write_reg = sp_write_reg32;
 		break;
 	case 2:
-		priv->read_reg = sp_read_reg16;
-		priv->write_reg = sp_write_reg16;
+		if (is_technologic) {
+			priv->read_reg = ts4800_read_reg16;
+			priv->write_reg = ts4800_write_reg16;
+		} else {
+			priv->read_reg = sp_read_reg16;
+			priv->write_reg = sp_write_reg16;
+		}
 		break;
 	case 1:	/* fallthrough */
 	default:
@@ -244,6 +269,7 @@ static int sp_remove(struct platform_device *pdev)
 
 static const struct of_device_id sp_of_table[] = {
 	{.compatible = "nxp,sja1000"},
+	{.compatible = "technologic,sja1000"},
 	{},
 };
 MODULE_DEVICE_TABLE(of, sp_of_table);
-- 
2.5.0

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