linux-kernel - [PATCH v4 4/7] clk: axi-clkgen: wrap limits in a struct and keep copy on the state object

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Message-ID: <20200929144417.89816-5-alexandru.ardelean@analog.com>
Date:   Tue, 29 Sep 2020 17:44:06 +0300
From:   Alexandru Ardelean <alexandru.ardelean@...log.com>
To:     <linux-clk@...r.kernel.org>, <linux-fpga@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <mturquette@...libre.com>, <sboyd@...nel.org>, <mdf@...nel.org>,
        <ardeleanalex@...il.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>
Subject: [PATCH v4 4/7] clk: axi-clkgen: wrap limits in a struct and keep copy on the state object

Up until the these limits were global/hard-coded, since they are typically
limits of the fabric.

However, since this is an FPGA generated clock, this may run on setups
where one clock is on a fabric, and another one synthesized on another
fabric connected via PCIe, and then these limits need to be adjusted for
each instance of the AXI clock.

This change wraps the current constants in 'axi_clkgen_limits' struct and
the 'axi_clkgen' instance keeps a copy of these limits, which is
initialized at probe from the default limits.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
---
 drivers/clk/clk-axi-clkgen.c | 39 ++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/drivers/clk/clk-axi-clkgen.c b/drivers/clk/clk-axi-clkgen.c
index 14d803e6af62..4342b7735590 100644
--- a/drivers/clk/clk-axi-clkgen.c
+++ b/drivers/clk/clk-axi-clkgen.c
@@ -46,9 +46,17 @@
 #define MMCM_CLK_DIV_DIVIDE	BIT(11)
 #define MMCM_CLK_DIV_NOCOUNT	BIT(12)
 
+struct axi_clkgen_limits {
+	unsigned int fpfd_min;
+	unsigned int fpfd_max;
+	unsigned int fvco_min;
+	unsigned int fvco_max;
+};
+
 struct axi_clkgen {
 	void __iomem *base;
 	struct clk_hw clk_hw;
+	struct axi_clkgen_limits limits;
 };
 
 static uint32_t axi_clkgen_lookup_filter(unsigned int m)
@@ -100,12 +108,15 @@ static uint32_t axi_clkgen_lookup_lock(unsigned int m)
 	return 0x1f1f00fa;
 }
 
-static const unsigned int fpfd_min = 10000;
-static const unsigned int fpfd_max = 300000;
-static const unsigned int fvco_min = 600000;
-static const unsigned int fvco_max = 1200000;
+static const struct axi_clkgen_limits axi_clkgen_default_limits = {
+	.fpfd_min = 10000,
+	.fpfd_max = 300000,
+	.fvco_min = 600000,
+	.fvco_max = 1200000,
+};
 
-static void axi_clkgen_calc_params(unsigned long fin, unsigned long fout,
+static void axi_clkgen_calc_params(const struct axi_clkgen_limits *limits,
+	unsigned long fin, unsigned long fout,
 	unsigned int *best_d, unsigned int *best_m, unsigned int *best_dout)
 {
 	unsigned long d, d_min, d_max, _d_min, _d_max;
@@ -122,12 +133,12 @@ static void axi_clkgen_calc_params(unsigned long fin, unsigned long fout,
 	*best_m = 0;
 	*best_dout = 0;
 
-	d_min = max_t(unsigned long, DIV_ROUND_UP(fin, fpfd_max), 1);
-	d_max = min_t(unsigned long, fin / fpfd_min, 80);
+	d_min = max_t(unsigned long, DIV_ROUND_UP(fin, limits->fpfd_max), 1);
+	d_max = min_t(unsigned long, fin / limits->fpfd_min, 80);
 
 again:
-	fvco_min_fract = fvco_min << fract_shift;
-	fvco_max_fract = fvco_max << fract_shift;
+	fvco_min_fract = limits->fvco_min << fract_shift;
+	fvco_max_fract = limits->fvco_max << fract_shift;
 
 	m_min = max_t(unsigned long, DIV_ROUND_UP(fvco_min_fract, fin) * d_min, 1);
 	m_max = min_t(unsigned long, fvco_max_fract * d_max / fin, 64 << fract_shift);
@@ -319,6 +330,7 @@ static int axi_clkgen_set_rate(struct clk_hw *clk_hw,
 	unsigned long rate, unsigned long parent_rate)
 {
 	struct axi_clkgen *axi_clkgen = clk_hw_to_axi_clkgen(clk_hw);
+	const struct axi_clkgen_limits *limits = &axi_clkgen->limits;
 	unsigned int d, m, dout;
 	struct axi_clkgen_div_params params;
 	uint32_t power = 0;
@@ -328,7 +340,7 @@ static int axi_clkgen_set_rate(struct clk_hw *clk_hw,
 	if (parent_rate == 0 || rate == 0)
 		return -EINVAL;
 
-	axi_clkgen_calc_params(parent_rate, rate, &d, &m, &dout);
+	axi_clkgen_calc_params(limits, parent_rate, rate, &d, &m, &dout);
 
 	if (d == 0 || dout == 0 || m == 0)
 		return -EINVAL;
@@ -368,10 +380,12 @@ static int axi_clkgen_set_rate(struct clk_hw *clk_hw,
 static long axi_clkgen_round_rate(struct clk_hw *hw, unsigned long rate,
 	unsigned long *parent_rate)
 {
+	struct axi_clkgen *axi_clkgen = clk_hw_to_axi_clkgen(hw);
+	const struct axi_clkgen_limits *limits = &axi_clkgen->limits;
 	unsigned int d, m, dout;
 	unsigned long long tmp;
 
-	axi_clkgen_calc_params(*parent_rate, rate, &d, &m, &dout);
+	axi_clkgen_calc_params(limits, *parent_rate, rate, &d, &m, &dout);
 
 	if (d == 0 || dout == 0 || m == 0)
 		return -EINVAL;
@@ -527,6 +541,9 @@ static int axi_clkgen_probe(struct platform_device *pdev)
 			return -EINVAL;
 	}
 
+	memcpy(&axi_clkgen->limits, &axi_clkgen_default_limits,
+	       sizeof(axi_clkgen->limits));
+
 	clk_name = pdev->dev.of_node->name;
 	of_property_read_string(pdev->dev.of_node, "clock-output-names",
 		&clk_name);
-- 
2.17.1