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Subject[PATCH v2 2/2] clk: fsl-sai: new driver
Date
With this driver it is possible to use the BCLK pin of the SAI module as
a generic clock output. This is esp. useful if you want to drive a clock
to an audio codec. Because the output only allows integer divider values
the audio codec needs an integrated PLL.

Signed-off-by: Michael Walle <michael@walle.cc>
---
changes since v1:
- none

drivers/clk/Kconfig | 12 ++++++
drivers/clk/Makefile | 1 +
drivers/clk/clk-fsl-sai.c | 84 +++++++++++++++++++++++++++++++++++++++
3 files changed, 97 insertions(+)
create mode 100644 drivers/clk/clk-fsl-sai.c

diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 45653a0e6ecd..dd1a5abc4ce8 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -174,6 +174,18 @@ config COMMON_CLK_CS2000_CP
help
If you say yes here you get support for the CS2000 clock multiplier.

+config COMMON_CLK_FSL_SAI
+ bool "Clock driver for BCLK of Freescale SAI cores"
+ depends on ARCH_LAYERSCAPE || COMPILE_TEST
+ help
+ This driver supports the Freescale SAI (Synchronous Audio Interface)
+ to be used as a generic clock output. Some SoCs have restrictions
+ regarding the possible pin multiplexer settings. Eg. on some SoCs
+ two SAI interfaces can only be enabled together. If just one is
+ needed, the BCLK pin of the second one can be used as general
+ purpose clock output. Ideally, it can be used to drive an audio
+ codec (sometimes known as MCLK).
+
config COMMON_CLK_GEMINI
bool "Clock driver for Cortina Systems Gemini SoC"
depends on ARCH_GEMINI || COMPILE_TEST
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 0696a0c1ab58..ec23fd956228 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_ARCH_CLPS711X) += clk-clps711x.o
obj-$(CONFIG_COMMON_CLK_CS2000_CP) += clk-cs2000-cp.o
obj-$(CONFIG_ARCH_EFM32) += clk-efm32gg.o
obj-$(CONFIG_COMMON_CLK_FIXED_MMIO) += clk-fixed-mmio.o
+obj-$(CONFIG_COMMON_CLK_FSL_SAI) += clk-fsl-sai.o
obj-$(CONFIG_COMMON_CLK_GEMINI) += clk-gemini.o
obj-$(CONFIG_COMMON_CLK_ASPEED) += clk-aspeed.o
obj-$(CONFIG_MACH_ASPEED_G6) += clk-ast2600.o
diff --git a/drivers/clk/clk-fsl-sai.c b/drivers/clk/clk-fsl-sai.c
new file mode 100644
index 000000000000..b92054d15ab1
--- /dev/null
+++ b/drivers/clk/clk-fsl-sai.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Freescale SAI BCLK as a generic clock driver
+ *
+ * Copyright 2019 Kontron Europe GmbH
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+
+#define I2S_CSR 0x00
+#define I2S_CR2 0x08
+#define CSR_BCE_BIT 28
+#define CR2_BCD BIT(24)
+#define CR2_DIV_SHIFT 0
+#define CR2_DIV_WIDTH 8
+
+struct fsl_sai_clk {
+ struct clk_divider div;
+ struct clk_gate gate;
+ spinlock_t lock;
+};
+
+static void __init fsl_sai_clk_setup(struct device_node *node)
+{
+ const char *clk_name = node->name;
+ struct fsl_sai_clk *sai_clk;
+ unsigned int num_parents;
+ const char *parent_name;
+ void __iomem *base;
+ struct clk_hw *hw;
+
+ num_parents = of_clk_get_parent_count(node);
+ if (!num_parents) {
+ pr_err("%s: no parent found", clk_name);
+ return;
+ }
+
+ parent_name = of_clk_get_parent_name(node, 0);
+
+ sai_clk = kzalloc(sizeof(*sai_clk), GFP_KERNEL);
+ if (!sai_clk)
+ return;
+
+ base = of_iomap(node, 0);
+ if (base == NULL) {
+ pr_err("%s: failed to map register space", clk_name);
+ goto err;
+ }
+
+ spin_lock_init(&sai_clk->lock);
+
+ sai_clk->gate.reg = base + I2S_CSR;
+ sai_clk->gate.bit_idx = CSR_BCE_BIT;
+ sai_clk->gate.lock = &sai_clk->lock;
+
+ sai_clk->div.reg = base + I2S_CR2;
+ sai_clk->div.shift = CR2_DIV_SHIFT;
+ sai_clk->div.width = CR2_DIV_WIDTH;
+ sai_clk->div.lock = &sai_clk->lock;
+
+ /* set clock direction, we are the BCLK master */
+ writel(CR2_BCD, base + I2S_CR2);
+
+ hw = clk_hw_register_composite(NULL, clk_name, &parent_name, 1,
+ NULL, NULL,
+ &sai_clk->div.hw, &clk_divider_ops,
+ &sai_clk->gate.hw, &clk_gate_ops,
+ CLK_SET_RATE_GATE);
+ if (IS_ERR(hw))
+ goto err;
+
+ of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
+
+ return;
+
+err:
+ kfree(sai_clk);
+}
+
+CLK_OF_DECLARE(fsl_sai_clk, "fsl,vf610-sai-clock", fsl_sai_clk_setup);
--
2.20.1
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