linux-kernel - [PATCHv4 1/2] spi: dw: add reset control

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Message-Id: <20200529155806.16758-1-dinguyen@kernel.org>
Date:   Fri, 29 May 2020 10:58:05 -0500
From:   Dinh Nguyen <dinguyen@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     dinguyen@...nel.org, devicetree@...r.kernel.org,
        linux-spi@...r.kernel.org, broonie@...nel.org, robh+dt@...nel.org,
        Sergey.Semin@...kalelectronics.ru, fancer.lancer@...il.com,
        andriy.shevchenko@...ux.intel.com, lars.povlsen@...rochip.com,
        liang.j.jin@...csson.com
Subject: [PATCHv4 1/2] spi: dw: add reset control

Add mechanism to get the reset control and deassert it in order to bring
the IP out of reset.

Signed-off-by: Liang Jin J <liang.j.jin@...csson.com>
Signed-off-by: Dinh Nguyen <dinguyen@...nel.org>
---
v4: no change
v3: allow for other failures
    remove tab for rstc reset_control
v2: use _get_optional_exclusive
    put IP back into reset if there was an error in probe function
---
 drivers/spi/spi-dw-mmio.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index 0894b4c09496..a1b87d4606ba 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -19,6 +19,7 @@
 #include <linux/acpi.h>
 #include <linux/property.h>
 #include <linux/regmap.h>
+#include <linux/reset.h>
 
 #include "spi-dw.h"
 
@@ -29,6 +30,7 @@ struct dw_spi_mmio {
 	struct clk     *clk;
 	struct clk     *pclk;
 	void           *priv;
+	struct reset_control *rstc;
 };
 
 #define MSCC_CPU_SYSTEM_CTRL_GENERAL_CTRL	0x24
@@ -224,6 +226,14 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 	if (ret)
 		goto out_clk;
 
+	/* find an optional reset controller */
+	dwsmmio->rstc = devm_reset_control_get_optional_exclusive(&pdev->dev, "spi");
+	if (IS_ERR(dwsmmio->rstc)) {
+		ret = PTR_ERR(dwsmmio->rstc);
+		goto out_clk;
+	}
+	reset_control_deassert(dwsmmio->rstc);
+
 	dws->bus_num = pdev->id;
 
 	dws->max_freq = clk_get_rate(dwsmmio->clk);
@@ -257,6 +267,8 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 	clk_disable_unprepare(dwsmmio->pclk);
 out_clk:
 	clk_disable_unprepare(dwsmmio->clk);
+	reset_control_assert(dwsmmio->rstc);
+
 	return ret;
 }
 
@@ -268,6 +280,7 @@ static int dw_spi_mmio_remove(struct platform_device *pdev)
 	pm_runtime_disable(&pdev->dev);
 	clk_disable_unprepare(dwsmmio->pclk);
 	clk_disable_unprepare(dwsmmio->clk);
+	reset_control_assert(dwsmmio->rstc);
 
 	return 0;
 }
-- 
2.17.1