[PATCH v2 3/3] can: sja1000: of: add compatibility with Technologic Systems version

[Damien Riegel <damien.riegel@savoirfairelinux.com>]

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@savoirfairelinux.com>
---
 drivers/net/can/sja1000/sja1000_platform.c | 47 ++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/drivers/net/can/sja1000/sja1000_platform.c b/drivers/net/can/sja1000/sja1000_platform.c
index e0572d0..bfb124d 100644
--- a/drivers/net/can/sja1000/sja1000_platform.c
+++ b/drivers/net/can/sja1000/sja1000_platform.c
@@ -45,6 +45,10 @@ struct sja1000_of_data {
 	int     (*init)(struct sja1000_priv *priv, struct device_node *of);
 };
 
+struct technologic_priv {
+	spinlock_t      io_lock;
+};
+
 static u8 sp_read_reg8(const struct sja1000_priv *priv, int reg)
 {
 	return ioread8(priv->reg_base + reg);
@@ -75,6 +79,43 @@ static void sp_write_reg32(const struct sja1000_priv *priv, int reg, u8 val)
 	iowrite8(val, priv->reg_base + reg * 4);
 }
 
+static u8 technologic_read_reg16(const struct sja1000_priv *priv, int reg)
+{
+	struct technologic_priv *tp = priv->priv;
+	unsigned long flags;
+	u8 val;
+
+	spin_lock_irqsave(&tp->io_lock, flags);
+	iowrite16(reg, priv->reg_base + 0);
+	val = ioread16(priv->reg_base + 2);
+	spin_unlock_irqrestore(&tp->io_lock, flags);
+
+	return val;
+}
+
+static void technologic_write_reg16(const struct sja1000_priv *priv,
+				    int reg, u8 val)
+{
+	struct technologic_priv *tp = priv->priv;
+	unsigned long flags;
+
+	spin_lock_irqsave(&tp->io_lock, flags);
+	iowrite16(reg, priv->reg_base + 0);
+	iowrite16(val, priv->reg_base + 2);
+	spin_unlock_irqrestore(&tp->io_lock, flags);
+}
+
+static int technologic_init(struct sja1000_priv *priv, struct device_node *of)
+{
+	struct technologic_priv *tp = priv->priv;
+
+	priv->read_reg = technologic_read_reg16;
+	priv->write_reg = technologic_write_reg16;
+	spin_lock_init(&tp->io_lock);
+
+	return 0;
+}
+
 static void sp_populate(struct sja1000_priv *priv,
 			struct sja1000_platform_data *pdata,
 			unsigned long resource_mem_flags)
@@ -255,8 +296,14 @@ static int sp_remove(struct platform_device *pdev)
 	return 0;
 }
 
+struct sja1000_of_data technologic_data = {
+	.priv_sz = sizeof(struct technologic_priv),
+	.init = technologic_init,
+};
+
 static const struct of_device_id sp_of_table[] = {
 	{.compatible = "nxp,sja1000"},
+	{.compatible = "technologic,sja1000", .data = &technologic_data},
 	{},
 };
 MODULE_DEVICE_TABLE(of, sp_of_table);
-- 
2.5.0