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Subject[PATCH v6 23/23] drivers/fsi: Use asynchronous slave mode
Date
From: Jeremy Kerr <jk@ozlabs.org>

For slaves that are behind a software-clocked master, we want FSI CFAMs
to run asynchronously to the FSI clock, so set up our slaves to be in
async mode.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Chris Bostic <cbostic@linux.vnet.ibm.com>
---
drivers/fsi/fsi-core.c | 22 +++++++++++++++++++++-
drivers/fsi/fsi-master-gpio.c | 1 +
drivers/fsi/fsi-master.h | 2 ++
3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index 747d0e3..a6ed34f 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -47,6 +47,7 @@
#define FSI_SMODE 0x0 /* R/W: Mode register */
#define FSI_SISC 0x8 /* R/W: Interrupt condition */
#define FSI_SSTAT 0x14 /* R : Slave status */
+#define FSI_LLMODE 0x100 /* R/W: Link layer mode register */

/*
* SMODE fields
@@ -62,6 +63,11 @@
#define FSI_SMODE_LBCRR_SHIFT 8 /* Clk ratio shift */
#define FSI_SMODE_LBCRR_MASK 0xf /* Clk ratio mask */

+/*
+ * LLMODE fields
+ */
+#define FSI_LLMODE_ASYNC 0x1
+
#define FSI_SLAVE_SIZE_23b 0x800000

static DEFINE_IDA(master_ida);
@@ -560,8 +566,8 @@ static void fsi_slave_release(struct device *dev)

static int fsi_slave_init(struct fsi_master *master, int link, uint8_t id)
{
+ uint32_t chip_id, llmode;
struct fsi_slave *slave;
- uint32_t chip_id;
uint8_t crc;
int rc;

@@ -597,6 +603,20 @@ static int fsi_slave_init(struct fsi_master *master, int link, uint8_t id)
return -ENODEV;
}

+ /* If we're behind a master that doesn't provide a self-running bus
+ * clock, put the slave into async mode
+ */
+ if (master->flags & FSI_MASTER_FLAG_SWCLOCK) {
+ llmode = cpu_to_be32(FSI_LLMODE_ASYNC);
+ rc = fsi_master_write(master, link, id,
+ FSI_SLAVE_BASE + FSI_LLMODE,
+ &llmode, sizeof(llmode));
+ if (rc)
+ dev_warn(&master->dev,
+ "can't set llmode on slave:%02x:%02x %d\n",
+ link, id, rc);
+ }
+
/* We can communicate with a slave; create the slave device and
* register.
*/
diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
index 5d9e0b0..d5cce88 100644
--- a/drivers/fsi/fsi-master-gpio.c
+++ b/drivers/fsi/fsi-master-gpio.c
@@ -569,6 +569,7 @@ static int fsi_master_gpio_probe(struct platform_device *pdev)
master->gpio_mux = gpio;

master->master.n_links = 1;
+ master->master.flags = FSI_MASTER_FLAG_SWCLOCK;
master->master.read = fsi_master_gpio_read;
master->master.write = fsi_master_gpio_write;
master->master.term = fsi_master_gpio_term;
diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h
index d6a4885..fd39924 100644
--- a/drivers/fsi/fsi-master.h
+++ b/drivers/fsi/fsi-master.h
@@ -19,6 +19,8 @@

#include <linux/device.h>

+#define FSI_MASTER_FLAG_SWCLOCK 0x1
+
struct fsi_master {
struct device dev;
int idx;
--
1.8.2.2
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