[PATCH 07/11] misc: support for serial slots in LP-8x4x

Sergei Ianovich
2013-12-01T06:28:51Z

Serial modules (I-870xxW series) implement DCON protocol which
allows one-master-many-slaves configuration over RS-485. When
these modules are installed into the device, they could be
accessed using the 2nd PXA built-in UART port (/dev/ttySA1).
However, it seems that addresses are not processed by the modules.
So the parallel bus needs to select which slot is connected.

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
---
Documentation/misc-devices/lp8x4x_bus.txt | 15 ++++++-
arch/arm/mach-pxa/include/mach/lp8x4x.h | 1 +
arch/arm/mach-pxa/lp8x4x.c | 7 ++-
drivers/misc/lp8x4x_bus.c | 73 +++++++++++++++++++++++++++++--
4 files changed, 90 insertions(+), 6 deletions(-)

diff --git a/Documentation/misc-devices/lp8x4x_bus.txt b/Documentation/misc-devices/lp8x4x_bus.txt
index f5392b3..d9a069d 100644
--- a/Documentation/misc-devices/lp8x4x_bus.txt
+++ b/Documentation/misc-devices/lp8x4x_bus.txt
@@ -19,7 +19,14 @@ LP-8x4x is an ARM-based industrial computer with a custom parallel bus to
connect expansion modules with digital input/output, analog input/output,
serial, CAN and other types of ports.

-The bus is implemented by a FPGA.
+The bus is implemented by a FPGA. There are two major groups of expansion
+modules: serial and parallel.
+
+Serial modules (I-870xxW series) implement DCON protocol which allows one-
+master-many-slaves configuration over RS-485. When these modules are installed
+into the device, they could be accessed using the 2nd PXA built-in UART port
+(/dev/ttySA1). However, it seems that addresses are not processed by
+the modules. So the parallel bus needs to select which slot is connected.

SYSFS
-----
@@ -28,3 +35,9 @@ SYSFS

slot_count
RO - shows total number of expansion slots on the device
+
+active_slot
+ RW - connects the select slot for serial communications. If there
+ is a parallel module in the selected slot, it simply ignores
+ incoming packets. So it is safe to activate any available
+ slot.
diff --git a/arch/arm/mach-pxa/include/mach/lp8x4x.h b/arch/arm/mach-pxa/include/mach/lp8x4x.h
index 5d289bf..9addfa8 100644
--- a/arch/arm/mach-pxa/include/mach/lp8x4x.h
+++ b/arch/arm/mach-pxa/include/mach/lp8x4x.h
@@ -37,6 +37,7 @@

/* board level registers in the FPGA */

+#define LP8X4X_SLOT_SWITCH 0x17009004
#define LP8X4X_EOI LP8X4X_P2V(0x17009006)
#define LP8X4X_INSINT LP8X4X_P2V(0x17009008)
#define LP8X4X_ENSYSINT LP8X4X_P2V(0x1700900A)
diff --git a/arch/arm/mach-pxa/lp8x4x.c b/arch/arm/mach-pxa/lp8x4x.c
index 38482d3..b30343d 100644
--- a/arch/arm/mach-pxa/lp8x4x.c
+++ b/arch/arm/mach-pxa/lp8x4x.c
@@ -424,6 +424,11 @@ static struct resource lp8x4x_bus_resources[] = {
.end = LP8X4X_MOD_NUM,
.flags = IORESOURCE_MEM,
},
+ [1] = {
+ .start = LP8X4X_SLOT_SWITCH,
+ .end = LP8X4X_SLOT_SWITCH,
+ .flags = IORESOURCE_MEM,
+ },
};

static struct platform_device lp8x4x_bus_device[] = {
@@ -431,7 +436,7 @@ static struct platform_device lp8x4x_bus_device[] = {
.name = "lp8x4x-bus",
.id = 0,
.resource = &lp8x4x_bus_resources[0],
- .num_resources = 1,
+ .num_resources = 2,
},
};

diff --git a/drivers/misc/lp8x4x_bus.c b/drivers/misc/lp8x4x_bus.c
index 9cd840e..647fde7 100644
--- a/drivers/misc/lp8x4x_bus.c
+++ b/drivers/misc/lp8x4x_bus.c
@@ -27,6 +27,8 @@ MODULE_DESCRIPTION("ICP DAS LP-8x4x parallel bus driver");
struct lp8x4x_master {
unsigned int slot_count;
void *count_addr;
+ unsigned int active_slot;
+ void *switch_addr;
struct device dev;
};

@@ -58,8 +60,45 @@ static ssize_t slot_count_show(struct device *dev,

static DEVICE_ATTR_RO(slot_count);

+static ssize_t active_slot_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct lp8x4x_master *m = container_of(dev, struct lp8x4x_master, dev);
+
+ return sprintf(buf, "%u\n", m->active_slot);
+}
+
+static ssize_t active_slot_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct lp8x4x_master *m = container_of(dev, struct lp8x4x_master, dev);
+ unsigned int active_slot = 0;
+ int err;
+
+ if (!buf)
+ return count;
+ if (0 == count)
+ return count;
+
+ err = kstrtouint(buf, 10, &active_slot);
+ if (err != 0 || !active_slot || active_slot > m->slot_count) {
+ dev_err(dev, "slot number is out of range 1..%u\n",
+ m->slot_count);
+ return count;
+ }
+
+ m->active_slot = active_slot;
+
+ iowrite8((1 << (m->active_slot - 1)) ^ 0xff, m->switch_addr);
+
+ return count;
+}
+
+static DEVICE_ATTR_RW(active_slot);
+
static struct attribute *master_dev_attrs[] = {
&dev_attr_slot_count.attr,
+ &dev_attr_active_slot.attr,
NULL,
};
ATTRIBUTE_GROUPS(master_dev);
@@ -69,10 +108,15 @@ static void devm_lp8x4x_bus_release(struct device *dev, void *res)
{
struct lp8x4x_master *m = *(struct lp8x4x_master **)res;
void *mem = m->count_addr;
+ void *mem2 = m->switch_addr;

dev_info(dev, "releasing devices\n");
device_unregister(&m->dev);
bus_unregister(&lp8x4x_bus_type);
+
+ /* Disable serial communications */
+ iowrite8(0xff, mem2);
+ iounmap(mem2);
iounmap(mem);
}

@@ -95,6 +139,7 @@ static int __init lp8x4x_bus_probe(struct platform_device *pdev)

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
+ dev_err(&pdev->dev, "Failed to get slot number address\n");
err = -ENODEV;
goto err2;
}
@@ -107,6 +152,21 @@ static int __init lp8x4x_bus_probe(struct platform_device *pdev)
goto err2;
}

+ res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+ if (!res) {
+ dev_err(&pdev->dev, "Failed to get slot switch address\n");
+ err = -ENODEV;
+ goto err3;
+ }
+
+ m->switch_addr = ioremap(res->start, resource_size(res));
+ if (!m->switch_addr) {
+ dev_err(&pdev->dev, "Failed to ioremap %p\n",
+ m->switch_addr);
+ err = -EFAULT;
+ goto err3;
+ }
+
m->slot_count = ioread8(m->count_addr);
switch (m->slot_count) {
case 1:
@@ -118,15 +178,18 @@ static int __init lp8x4x_bus_probe(struct platform_device *pdev)
default:
dev_info(&pdev->dev, "unexpected slot number(%u)",
m->slot_count);
- goto err3;
+ goto err_bus;
};

dev_info(&pdev->dev, "found bus with up to %u slots\n", m->slot_count);

+ /* Disable serial communications until explicitly enabled */
+ iowrite8(0xff, m->switch_addr);
+
err = bus_register(&lp8x4x_bus_type);
if (err < 0) {
dev_err(&pdev->dev, "failed to register bus type\n");
- goto err3;
+ goto err_bus;
}

m->dev.bus = &lp8x4x_bus_type;
@@ -138,14 +201,16 @@ static int __init lp8x4x_bus_probe(struct platform_device *pdev)
err = device_register(&m->dev);
if (err < 0) {
dev_err(&pdev->dev, "failed to register backplane device\n");
- goto err4;
+ goto err_dev;
}

devres_add(&pdev->dev, p);
return 0;

-err4:
+err_dev:
bus_unregister(&lp8x4x_bus_type);
+err_bus:
+ iounmap(m->switch_addr);
err3:
iounmap(m->count_addr);
err2:
--
1.8.4.2