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authorJoel Stanley <joel@jms.id.au>2017-11-01 10:53:30 +1030
committerWolfram Sang <wsa@the-dreams.de>2017-11-06 19:15:31 +0100
commitedd20e95bca4a5434f264d8ab40d729761479825 (patch)
tree0aec602dedb9c1c42ba9cb7cf838b065a8076d7e /drivers/i2c
parent7f2a2f0d0d66b2d834c793df45af3277bb5f10f4 (diff)
i2c: aspeed: Deassert reset in probe
In order to use i2c from a cold boot, the i2c peripheral must be taken out of reset. We request a shared reset controller each time a bus driver is loaded, as the reset is shared between the 14 i2c buses. On remove the reset is asserted, which only touches the hardware once the last i2c bus is removed. The reset is required as the I2C buses will not work without releasing the reset. Previously the driver only worked with out of tree hacks that released this reset before the driver was loaded. Update the device tree bindings to reflect this. Signed-off-by: Joel Stanley <joel@jms.id.au> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-aspeed.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index 284f8670dbeb..7d4aeb4465b3 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -27,6 +27,7 @@
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
+#include <linux/reset.h>
#include <linux/slab.h>
/* I2C Register */
@@ -132,6 +133,7 @@ struct aspeed_i2c_bus {
struct i2c_adapter adap;
struct device *dev;
void __iomem *base;
+ struct reset_control *rst;
/* Synchronizes I/O mem access to base. */
spinlock_t lock;
struct completion cmd_complete;
@@ -847,6 +849,14 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
/* We just need the clock rate, we don't actually use the clk object. */
devm_clk_put(&pdev->dev, parent_clk);
+ bus->rst = devm_reset_control_get_shared(&pdev->dev, NULL);
+ if (IS_ERR(bus->rst)) {
+ dev_err(&pdev->dev,
+ "missing or invalid reset controller device tree entry");
+ return PTR_ERR(bus->rst);
+ }
+ reset_control_deassert(bus->rst);
+
ret = of_property_read_u32(pdev->dev.of_node,
"bus-frequency", &bus->bus_frequency);
if (ret < 0) {
@@ -917,6 +927,8 @@ static int aspeed_i2c_remove_bus(struct platform_device *pdev)
spin_unlock_irqrestore(&bus->lock, flags);
+ reset_control_assert(bus->rst);
+
i2c_del_adapter(&bus->adap);
return 0;