net: phy: spi_ks8995: generalize creation of SPI commands

Prepare creating SPI reads and writes for other switch families.
The KS8995 family uses the straight forward
	<8bit CMD><8bit ADDR>
sequence.
To be able to support KSZ8795 family, which uses
	<3bit CMD><12bit ADDR><1 bit TR>
make the SPI command creation chip variant dependent.

Signed-off-by: Helmut Buchsbaum <helmut.buchsbaum@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/phy/spi_ks8995.c b/drivers/net/phy/spi_ks8995.c
index 8258c16..9dcc5b4 100644 (file)
--- a/drivers/net/phy/spi_ks8995.c
+++ b/drivers/net/phy/spi_ks8995.c
@@ -105,6 +105,8 @@ struct ks8995_chip_params {
        int family_id;
        int chip_id;
        int regs_size;
+       int addr_width;
+       int addr_shift;
 };
 
 static const struct ks8995_chip_params ks8995_chip[] = {
@@ -113,12 +115,16 @@ static const struct ks8995_chip_params ks8995_chip[] = {
                .family_id = FAMILY_KS8995,
                .chip_id = KS8995_CHIP_ID,
                .regs_size = KS8995_REGS_SIZE,
+               .addr_width = 8,
+               .addr_shift = 0,
        },
        [ksz8864] = {
                .name = "KSZ8864RMN",
                .family_id = FAMILY_KS8995,
                .chip_id = KSZ8864_CHIP_ID,
                .regs_size = KSZ8864_REGS_SIZE,
+               .addr_width = 8,
+               .addr_shift = 0,
        },
 };
 
@@ -153,20 +159,44 @@ static inline u8 get_chip_rev(u8 val)
        return (val >> ID1_REVISION_S) & ID1_REVISION_M;
 }
 
+/* create_spi_cmd - create a chip specific SPI command header
+ * @ks: pointer to switch instance
+ * @cmd: SPI command for switch
+ * @address: register address for command
+ *
+ * Different chip families use different bit pattern to address the switches
+ * registers:
+ *
+ * KS8995: 8bit command + 8bit address
+ * KSZ8795: 3bit command + 12bit address + 1bit TR (?)
+ */
+static inline __be16 create_spi_cmd(struct ks8995_switch *ks, int cmd,
+                                   unsigned address)
+{
+       u16 result = cmd;
+
+       /* make room for address (incl. address shift) */
+       result <<= ks->chip->addr_width + ks->chip->addr_shift;
+       /* add address */
+       result |= address << ks->chip->addr_shift;
+       /* SPI protocol needs big endian */
+       return cpu_to_be16(result);
+}
 /* ------------------------------------------------------------------------ */
 static int ks8995_read(struct ks8995_switch *ks, char *buf,
                 unsigned offset, size_t count)
 {
-       u8 cmd[2];
+       __be16 cmd;
        struct spi_transfer t[2];
        struct spi_message m;
        int err;
 
+       cmd = create_spi_cmd(ks, KS8995_CMD_READ, offset);
        spi_message_init(&m);
 
        memset(&t, 0, sizeof(t));
 
-       t[0].tx_buf = cmd;
+       t[0].tx_buf = &cmd;
        t[0].len = sizeof(cmd);
        spi_message_add_tail(&t[0], &m);
 
@@ -174,9 +204,6 @@ static int ks8995_read(struct ks8995_switch *ks, char *buf,
        t[1].len = count;
        spi_message_add_tail(&t[1], &m);
 
-       cmd[0] = KS8995_CMD_READ;
-       cmd[1] = offset;
-
        mutex_lock(&ks->lock);
        err = spi_sync(ks->spi, &m);
        mutex_unlock(&ks->lock);
@@ -184,20 +211,20 @@ static int ks8995_read(struct ks8995_switch *ks, char *buf,
        return err ? err : count;
 }
 
-
 static int ks8995_write(struct ks8995_switch *ks, char *buf,
                 unsigned offset, size_t count)
 {
-       u8 cmd[2];
+       __be16 cmd;
        struct spi_transfer t[2];
        struct spi_message m;
        int err;
 
+       cmd = create_spi_cmd(ks, KS8995_CMD_WRITE, offset);
        spi_message_init(&m);
 
        memset(&t, 0, sizeof(t));
 
-       t[0].tx_buf = cmd;
+       t[0].tx_buf = &cmd;
        t[0].len = sizeof(cmd);
        spi_message_add_tail(&t[0], &m);
 
@@ -205,9 +232,6 @@ static int ks8995_write(struct ks8995_switch *ks, char *buf,
        t[1].len = count;
        spi_message_add_tail(&t[1], &m);
 
-       cmd[0] = KS8995_CMD_WRITE;
-       cmd[1] = offset;
-
        mutex_lock(&ks->lock);
        err = spi_sync(ks->spi, &m);
        mutex_unlock(&ks->lock);