[PATCH v6 3/3] can: sja1000: of: add compatibility with Technologic Systems version

[Marc Kleine-Budde]

From: Damien Riegel <damien.rie...@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.rie...@savoirfairelinux.com>
Signed-off-by: Marc Kleine-Budde <m...@pengutronix.de>
---
 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 777d312f1779..dc9c6db96c3c 100644
--- a/drivers/net/can/sja1000/sja1000_platform.c
+++ b/drivers/net/can/sja1000/sja1000_platform.c
@@ -46,6 +46,10 @@ 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);
@@ -76,6 +80,43 @@ static void sp_write_reg32(const struct sja1000_priv *priv, 
int reg, u8 val)
        iowrite8(val, priv->reg_base + reg * 4);
 }
 
+static u8 sp_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 sp_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 sp_technologic_init(struct sja1000_priv *priv, struct device_node 
*of)
+{
+       struct technologic_priv *tp = priv->priv;
+
+       priv->read_reg = sp_technologic_read_reg16;
+       priv->write_reg = sp_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)
@@ -160,8 +201,14 @@ static void sp_populate_of(struct sja1000_priv *priv, 
struct device_node *of)
                priv->cdr |= CDR_CBP; /* default */
 }
 
+static struct sja1000_of_data technologic_data = {
+       .priv_sz = sizeof(struct technologic_priv),
+       .init = sp_technologic_init,
+};
+
 static const struct of_device_id sp_of_table[] = {
        { .compatible = "nxp,sja1000", .data = NULL, },
+       { .compatible = "technologic,sja1000", .data = &technologic_data, },
        { /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, sp_of_table);
-- 
2.7.0.rc3