From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dinh Nguyen Subject: [PATCH] drivers/amba: add reset control to primecell probe Date: Thu, 1 Aug 2019 13:43:46 -0500 Message-ID: <20190801184346.7015-1-dinguyen@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Sender: linux-kernel-owner@vger.kernel.org To: devicetree@vger.kernel.org Cc: dinguyen@kernel.org, linux-kernel@vger.kernel.org, robh+dt@kernel.org, frowand.list@gmail.com, keescook@chromium.org, anton@enomsg.org, ccross@android.com, tony.luck@intel.com, Dinh Nguyen List-Id: devicetree@vger.kernel.org From: Dinh Nguyen The primecell controller on some SoCs, i.e. SoCFPGA, is held in reset by default. Until recently, the DMA controller was brought out of reset by the bootloader(i.e. U-Boot). But a recent change in U-Boot, the peripherals that are not used are held in reset and are left to Linux to bring them out of reset. Add a mechanism for getting the reset property and de-assert the primecell module from reset if found. This is a not a hard fail if the reset property is not present in the device tree node, so the driver will continue to probe. Signed-off-by: Dinh Nguyen --- drivers/of/platform.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/of/platform.c b/drivers/of/platform.c index 7801e25e6895..d8945705313d 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -21,6 +21,7 @@ #include #include #include +#include const struct of_device_id of_default_bus_match_table[] = { { .compatible = "simple-bus", }, @@ -229,6 +230,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node, struct amba_device *dev; const void *prop; int i, ret; + struct reset_control *rstc; pr_debug("Creating amba device %pOF\n", node); @@ -270,6 +272,18 @@ static struct amba_device *of_amba_device_create(struct device_node *node, goto err_free; } + /* + * reset control of the primecell block is optional + * and will not fail if the reset property is not found. + */ + rstc = of_reset_control_get_exclusive(node, "dma"); + if (!IS_ERR(rstc)) { + reset_control_deassert(rstc); + reset_control_put(rstc); + } else { + pr_debug("amba: reset control not found\n"); + } + ret = amba_device_add(dev, &iomem_resource); if (ret) { pr_err("amba_device_add() failed (%d) for %pOF\n", -- 2.20.0