[PATCH v2] ipmi: bt-bmc: Use a regmap for register access

From: Andrew Jeffery
Date: Mon Feb 20 2017 - 10:24:56 EST

The registers for the bt-bmc device live under the Aspeed LPC
controller. Devicetree bindings have recently been introduced for the
LPC controller where the "host" portion of the LPC register space is
described as a syscon device. Future devicetrees describing the bt-bmc
device should nest its node under the appropriate "simple-mfd", "syscon"
compatible node.

This change allows the bt-bmc driver to function with both syscon and
non-syscon- based devicetree descriptions by always using a regmap for
register access, either retrieved from the parent syscon device or
instantiated if none exists.

Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx>
Reviewed-by: CÃdric Le Goater <clg@xxxxxxxx>
---

v2: Address Joel's review with some minor cleanups

* Add '|| COMPILE_TEST' to Kconfig depends
* Const-ify the regmap configuration struct
* Remove some redundant output from the WARN formatting

Propagating regmap_{read,write}() failures makes the change more invasive than
I would like, so I have favoured keeping the WARN()s

drivers/char/ipmi/Kconfig | 3 +-
drivers/char/ipmi/bt-bmc.c | 80 ++++++++++++++++++++++++++++++++++------------
2 files changed, 61 insertions(+), 22 deletions(-)

diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index 7f816655cbbf..90f3edffb067 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -78,7 +78,8 @@ config IPMI_POWEROFF
endif # IPMI_HANDLER

config ASPEED_BT_IPMI_BMC
- depends on ARCH_ASPEED
+ depends on ARCH_ASPEED || COMPILE_TEST
+ depends on REGMAP && REGMAP_MMIO && MFD_SYSCON
tristate "BT IPMI bmc driver"
help
Provides a driver for the BT (Block Transfer) IPMI interface
diff --git a/drivers/char/ipmi/bt-bmc.c b/drivers/char/ipmi/bt-bmc.c
index fc9e8891eae3..d6f5d9eb102d 100644
--- a/drivers/char/ipmi/bt-bmc.c
+++ b/drivers/char/ipmi/bt-bmc.c
@@ -12,10 +12,13 @@
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/io.h>
+#include <linux/mfd/syscon.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
+#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
+#include <linux/regmap.h>
#include <linux/sched.h>
#include <linux/timer.h>

@@ -60,7 +63,8 @@
struct bt_bmc {
struct device dev;
struct miscdevice miscdev;
- void __iomem *base;
+ struct regmap *map;
+ int offset;
int irq;
wait_queue_head_t queue;
struct timer_list poll_timer;
@@ -69,14 +73,29 @@ struct bt_bmc {

static atomic_t open_count = ATOMIC_INIT(0);

+static const struct regmap_config bt_regmap_cfg = {
+ .reg_bits = 32,
+ .val_bits = 32,
+ .reg_stride = 4,
+};
+
static u8 bt_inb(struct bt_bmc *bt_bmc, int reg)
{
- return ioread8(bt_bmc->base + reg);
+ uint32_t val = 0;
+ int rc;
+
+ rc = regmap_read(bt_bmc->map, bt_bmc->offset + reg, &val);
+ WARN(rc != 0, "regmap_read() failed: %d\n", rc);
+
+ return rc == 0 ? (u8) val : 0;
}

static void bt_outb(struct bt_bmc *bt_bmc, u8 data, int reg)
{
- iowrite8(data, bt_bmc->base + reg);
+ int rc;
+
+ rc = regmap_write(bt_bmc->map, bt_bmc->offset + reg, data);
+ WARN(rc != 0, "regmap_write() failed: %d\n", rc);
}

static void clr_rd_ptr(struct bt_bmc *bt_bmc)
@@ -367,14 +386,18 @@ static irqreturn_t bt_bmc_irq(int irq, void *arg)
{
struct bt_bmc *bt_bmc = arg;
u32 reg;
+ int rc;
+
+ rc = regmap_read(bt_bmc->map, bt_bmc->offset + BT_CR2, &reg);
+ if (rc)
+ return IRQ_NONE;

- reg = ioread32(bt_bmc->base + BT_CR2);
reg &= BT_CR2_IRQ_H2B | BT_CR2_IRQ_HBUSY;
if (!reg)
return IRQ_NONE;

/* ack pending IRQs */
- iowrite32(reg, bt_bmc->base + BT_CR2);
+ regmap_write(bt_bmc->map, bt_bmc->offset + BT_CR2, reg);

wake_up(&bt_bmc->queue);
return IRQ_HANDLED;
@@ -384,7 +407,6 @@ static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
- u32 reg;
int rc;

bt_bmc->irq = platform_get_irq(pdev, 0);
@@ -405,18 +427,17 @@ static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
* will be cleared (along with B2H) when we can write the next
* message to the BT buffer
*/
- reg = ioread32(bt_bmc->base + BT_CR1);
- reg |= BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY;
- iowrite32(reg, bt_bmc->base + BT_CR1);
+ rc = regmap_update_bits(bt_bmc->map, bt_bmc->offset + BT_CR1,
+ (BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY),
+ (BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY));

- return 0;
+ return rc;
}

static int bt_bmc_probe(struct platform_device *pdev)
{
struct bt_bmc *bt_bmc;
struct device *dev;
- struct resource *res;
int rc;

if (!pdev || !pdev->dev.of_node)
@@ -431,10 +452,27 @@ static int bt_bmc_probe(struct platform_device *pdev)

dev_set_drvdata(&pdev->dev, bt_bmc);

- res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- bt_bmc->base = devm_ioremap_resource(&pdev->dev, res);
- if (IS_ERR(bt_bmc->base))
- return PTR_ERR(bt_bmc->base);
+ bt_bmc->map = syscon_node_to_regmap(pdev->dev.parent->of_node);
+ if (IS_ERR(bt_bmc->map)) {
+ struct resource *res;
+ void __iomem *base;
+
+ /*
+ * Assume it's not the MFD-based devicetree description, in
+ * which case generate a regmap ourselves
+ */
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ bt_bmc->map = devm_regmap_init_mmio(dev, base, &bt_regmap_cfg);
+ bt_bmc->offset = 0;
+ } else {
+ rc = of_property_read_u32(dev->of_node, "reg", &bt_bmc->offset);
+ if (rc)
+ return rc;
+ }

mutex_init(&bt_bmc->mutex);
init_waitqueue_head(&bt_bmc->queue);
@@ -461,12 +499,12 @@ static int bt_bmc_probe(struct platform_device *pdev)
add_timer(&bt_bmc->poll_timer);
}

- iowrite32((BT_IO_BASE << BT_CR0_IO_BASE) |
- (BT_IRQ << BT_CR0_IRQ) |
- BT_CR0_EN_CLR_SLV_RDP |
- BT_CR0_EN_CLR_SLV_WRP |
- BT_CR0_ENABLE_IBT,
- bt_bmc->base + BT_CR0);
+ regmap_write(bt_bmc->map, bt_bmc->offset + BT_CR0,
+ (BT_IO_BASE << BT_CR0_IO_BASE) |
+ (BT_IRQ << BT_CR0_IRQ) |
+ BT_CR0_EN_CLR_SLV_RDP |
+ BT_CR0_EN_CLR_SLV_WRP |
+ BT_CR0_ENABLE_IBT);

clr_b_busy(bt_bmc);

--
2.9.3